It's obvious, it's a rip in the much-quoted Einsteins
FABRIC of space-time. LOL.
On the serious side there's a theory called the Big Rip, buts it's different to what you are proposing. In the Big Rip, as space continues to accelerate at an ever-increasing rate, it's suggested that the repulsive force of dark energy becomes so great that it eventually expands the space between the atoms constituent parts and rips them apart, and also spacetime as well. So in this theory, space-time is treated as something you can rip apart.
Also there another theory that the universe is in a state of 'false vacuum' energy, and that it might one day suddenly collapse into a more stable 'true vacuum' state, obliterating everything.
en.wikipedia.org
en.wikipedia.org
My own thoughts are that as space expands it just gets thinner. Something must happen. If space consists of particles, they will just disperse but if space consists of quantum fields/quantum foam (current thinking), then what happens if such fields keep stretching? somethings got to give. I personally don't think things will get that far as I believe in some kind of collapse/crunch or cyclic universe.