They might limit supply early on but they also increase supply when they later sell the tickets, so the net effect on supply is zero (unless they leave many tickets unsold, which would be stupid of them).
Why not? No law of physics prevents it and we already have examples of (albeit simpler) organisms that can live forever. Worst case scenario, we grow a clone of your body, transplant your brain into it, then somehow repair the spinal cord and slowly replace your brain tissue piece-by-piece. Might be a difficult engineering challenge but it’s 100% possible.