Well that would be almost impossible, as the less btc would be available to buy, the more valuable it would be. But imagine what would happen if a one could eventually buy the 100% supply? i think, in my honest opinion that it would then drop to nearly zero value.
No more pair to make with btc in trading as there were no more circulating supply, the entire community would eventually move to another coin and make that coin the strong traiding pair. The puersue for btc would eventually stop because you would know that even if you buy back 10 or 20 or 30% of there would always be one guy with more than 51% that could make the price as he want.