What if all cryptocurrencies merged together? Cuz if it merges, then the price of Bitcoin would pass $100,000? The market cap would be at $3 trillion dollars but what will the price be for 1 coin?
If this impossibility were ever to happen (if ever) that means monotony will be the order of the day with cryptocurrency. That will surely suck. Come to think of it, what then happens with Bitcoin the pathfinder without a smart contract? This industry is able to grow to this level because ETH's smart contract allowed other projects to spring up and that is replicated across with some newer projects allowing others too.This sounds like the most stupid idea I've ever seen. 
But of course, this is all hypothesis. OP is just trying to get confusion out of their body system.