Several stable coins will die horribly. Tether is one bad revelation away from non-existence.

Privacy coins ARRR / XMR have two paths depending on which collapses first.
If cryptos take off, while govern-cement is still around and cracks down, then privacy coins will skyrocket.
... BUT! privacy may be added to BTC lightning network first, and then... what's it good for?

ETH might kill itself.
Far more likely then an ETH killer coming along.
But really, those kinda go hand in hand. An opportunity... and something there to take advantage of it.

The biggest thing will be whatever the wealthy people choose as the new banking system.
My bet is on XRP
but remember, there will come a time when all the wealthy and their money laundering get exposed, and that may destroy the token they use. Or worse yet, they may lock it up not allowing the goyim in anymore.