It's interesting to view it that way. I was actually thinking the opposite - that if the wealthy people own almost all the coins then it will become completely obsolete (simply because the coins aren't being used and because what drives something to rise in value is popularity, only a fraction of the world's population is elite wealthy). I would think we would go with another cryto far before that happened though.
That is if only they own all the coin. If there is still coins in circulation, Bitcoin cannot die.
Bitcoin works on the principles of supply and demand. If the rich people own majority of the coins and decides not to touch them, the remaining coins will become more valuable since the supply of it becomes scarce. There is no problem with it, we can easily increase the number of decimals and people would continue to use Bitcoins in small denominations.