The Bitcoin price will be very high as the supply of Bitcoin is limited and the ownership of 1BTC at that time will be very difficult.
Yes you are right, in my opinion the blockchain and decentralization will exist, but not all people will find attractive to use, only those ones who have to keep their identity. Will they be good or bad people that is other question
Problem is that whole system relies on miners and if they don't find profit they will leave system, though history shows that catastrophic situations from films (like all machines will rise against humans) don't happen.
During the time ASIC miners will become cheaper according to Moor's law, which is great!