Yes, we cannot predict what science might show us in the future but we can rule certain things out. FTL travel, violations of the Second Law, etc.
Yes, there are patents on such things but patent claims do not have to work. (Perpetual motion claims are an exception, any such claim must be accompanied by a working model)
Yes, people are working on such claims but that does not mean the claims will ever bear fruit.
In every case where a new solution to one of Einstein's equations is found, such that a forbidden thing can now occur, there is always a caveat the includes another impossible thing to happen.
1)Wormholes which allow instantaneous travel to anywhere in the universe. Caveats include that you must go to the far end first, in order to make the exit of the wormhole. Also, you must completely destroy yourself by falling into a black hole.
2) FTL travel requires you to go back in time.
3) FTL travel requires negative mass.