What will happen at some point, is that many people who were formerly enthusiastic about bitcoin and many altcoins, will realize that it's mostly a bubble inflated by market manipulation, that the original purpose - an alternative way to exchange value - is not being fulfilled very much (either because the bubble will be that much inflated or because someone will invent more efficient way to exchange actual value).

And then, they realize that they have to exchange their cryptocurrencies for some less volatile fiat currency sooner than all other people realize the same and the bubble pops. Because the goal of most people participating in this market is not to find an alternative for fiat currency, but to get rich, preferably quickly, preferably in fiat currency measures.