How do you think the crypto use would evolve ?

For the moment, I see it as a new way to speculate. Here, we are asked to declare it for our tax income. In other countries, the use is forbidden. So, in any case, the state tries to keep control on it, which limits usability and adoption.

I think it could be a protection against inflation or deflation, (even if it has its own volatility), as it is not indexed on a specific money providing a form of local stability.

However, PoS or PoW, it is almost the same. Big/rich have the capability to invest / buy machines while poor cannot. So one or the other option seems equivalent.

PoS is important for adoption. regarding investing you can join a pool you don't have to have your own dedicated miner - pooling is even encouraged to secure the protocol.