Wow, Bill! Stirring the pot, again, I see...
Lots of good and bad ideas so far. I would maybe comment only on a few of them.
I am not an anti NASA guy either. I think it has its place, and certainly, might be the best sort of model for interplanetary exploration (Cassini, New Horizons etc.), space telescopes (Hubble, Spitzer and others) and the likes of the Martian rovers, whether alone or in partnership with other space agencies. But it seems it is hobbled and at a great disadvantage when dealing with any sort of long term, ongoing strategy for its missions. One President proposes a "Vision" and NASA begs Congress for the money, only to find the next iteration of Congress has total amnesia when it comes to remembering what NASA needs to fulfill its mandate.
Perhaps NASA would be fine if it was reorganized or replaced by another agency that was more insulated from changing political winds. How wonderful it would be if space exploration was constitutionally allotted a fixed amount of GNP (1% perhaps?) that varied with the health and growth of the economy and not with porkbarreling and short term political whims.
As far as a corporation for space related efforts is concerned, I agree with many others that the "space business" is a hard thing to try to wedge into the conventional business plan with an expectation of profit over a specified period of time. I wonder if a better approach might be to have a non-profit foundation or an independent quasi-multi-governmental agency established to pursue space related activities. Hopefully some initial seed money could be raised from various private and governmental sources, and a properly run ongoing fund raising and merchandising operation to expand and sustain it could be started. Perhaps it would not undertake missions directly, but make funding available for others to do them. In a sense, this is already happening with the X-Prizes and the like, but maybe the concept could be expanded further. I have no idea what the ultimately best form is that it should take, but above all it should be beyond the reach of elected politicians after it is started.
As far as getting rich off asteroid mining, I see that a very long way off. To exploit asteroids and return the material to Earth is one of the farthest I can see, short of actually changing the orbit of any body beyond a few meters in size to a preferred orbit of our choosing. The best use of them with be in fabrication of things for use in space, whether that be building space craft in space or creating large space stations/colonies there and so avoiding the cost of launching large amounts of material from Earth.
Ultimately, the idea of making a buck up there in the short term is likely limited to ever cheaper contracts for launches, space tourism and commercial communication projects. It will be a long while yet before we have the technology to send a robotic mission to any body in space to have it mine and process whatever may be there into usable commodities. Even extracting water from icy asteroids or comets is not yet possible, let alone turning that into rocket fuel that is ultimately in a location and orbit that is useful to other endeavours.
Private enterprise will never be interested in landing probes on the moons of gas giants to see what may be there or trying to make money selling pictures from space telescopes of various kinds or sending missions beyond the solar system with no prospect of coming back.
I see a strong case to be made for both public and private space exploration. I am not yet sure in my own mind which will facilitate human space exploration best at this point. Neither have really accomplished much in that regard to be very proud of recently. For pure science purposes, I do believe that robots can do the job far cheaper than can be done by sending and returning people to do the same tasks. And I think many that disagree with me there often forget how young robotic technology truly is, and how far it will likely advance in the coming years and decades, while conveniently forgetting that human evolution is already a few million years into the process, and not likely to progress noticeably much in the future except one generation at a time.
The usual next objection I expect to hear is from the die hard "space must be quickly colonized at any cost" crowd to me not joining into their specious chants is that we simply have no options in our solar system with our technology, nor will we in our grandchildren's lifetimes to establish and support a colony of this planet. We could, conceivably, establish a base on either the Moon or Mars at great expense much like a smaller version of what we have on Antarctica. We have been there over 50 years and still few have stayed there longer than a few years. Most go for the summer and leave again within 6 months. The total human population there varies from about 1000 - 5000 people. I realize there are many things about the two situations that are totally different, but the similarities are worth noting. Antarctica is both easy to go to and easy to get off of if needed than an extra terrestrial colony would be. Human settlement is restricted by international treaty, so that those there are primarily there for scientific research, without colonization being an option. There are many other differences.
But the similarities are also there. To be independently sustainable both would need to grow a food supply to sustain themselves. Antarctica can get by on semi annual care packages so crop growing and animal raising is not necessary. I would say it will take a long time to produce a local food supply on the Moon or Mars without it taking all the human effort available to do so. Most initial materials for shelter will be sent from here before manufacturing more from local materials is feasible. It will be a very long time until there is a surplus of ANYTHING that is needed to help support an expanded population beyond the initial people, without all their needs coming from Earth as well. How long that will take is anyone's guess, but it won't happen overnight.
The usual prattle goes on and on about how if we don't get a colony established on Mars soon an asteroid will come along and wipe us all out, and so civilization will end. Get a grip! That is the most specious of all! To say that all mankind would be wiped out like the dinosaurs if an asteroid hit is like saying we are only as smart as they were and our technology is is no better than theirs was. If 99.9% of humanity was wiped out, that would still leave several million survivors. That is far more than what is likely to be on Mars for several centuries, if ever.
But, suppose that ALL human life was extinguished on the Earth. Do you think for a minute that several thousand people living on Mars would have all the elements that make up human civilization to carry on with? Gone are all the libraries, universities, museums and all the architecture, plus all the scientific, engineering and medical research facilities, as well as all the art and musicians and all the other things that make up a civilization. I seriously doubt a fraction of a percent of human knowledge will be on Mars at that time, if ever. There may be a vast collection of DVD's or the equivalent such thing of the day, and some sample Earth artifacts hanging on the walls of Martian habitats, but I doubt very many, considering the cost of sending them there.
I think that even a well established Martian colony will still need the Earth to trade with to survive, if not to send them vital supplies on a regular basis. Perhaps they would survive and carry on, eventually being able to build return rockets to come back to repopulate Earth years later. My personal feeling is that we will set up a base on Mars, spend years proving it could be done, then something will come along which will mean for a while Earth is unable or unwilling to support the colony. Either the people there will be told to abandon it and return, or be abandoned there without support. It may be that after a couple decades we say it was fun but decide to call it quits, or we maintain a few dozen people in a scaled down version of Antarctica.
To really be able to say humans will not just survive, but thrive in a colony off the Earth will likely be possible in the VERY distant future when we have identified suitable exo-planets and send some very brave people on a very long one way trip.
Whatever the reasons we try to set up bases or colonies off the Earth I just hope we do it for honest ones. To hear people constantly say: It must be done! (especially MY way) We must must do it to save humanity! (MY research grant) We will all die if we don't! (but not ME, I won't be here if you fund ME like I want) To get up on a soap box and preach that this is imperative is the BEST way to begin a massive waste of money and talent that leads to the sort of backlash that gets the possibility of it ever happening canceled indefinitely.
I also don't see that going to live on Mars will be very lucrative for a private venture for a very long time.