In the first place — why would 'blockchain' not survive? Blockchains will work totally fine without mixers and coinjoins and stuff. I'm all for privacy, but everyone simply isn't interested in it whether we like it or not. Only a minority cares about self-custody and being self-sovereign; a lot of people just want to use it just as an investment/hedge.
And yes, even without privacy, Bitcoin and blockchains would still be useful, just as these are still very useful today despite privacy being very minimal.
Blockchains work "fine", I agree. And as I wrote above, I don't see anything about them changing in the short term.
But long term, the entire reason you resort to the blockchain architecture is to make the system resistant to government subpoenas. If you didn't want that benefit, a centralized system is far better in every single way.
And here I am just talking about the
backend architecture, not digital currency trading in general, which I very much am banking on--personally--to remain a very big part of consumer life

. You can absolutely have everything most consumers want out of cryptocurrencies without blockchain, but cheaper and faster and better.
So in the long run, if blockchain is just a useless addition to a product that makes it slower and more expensive, then that technology will eventually fall by the wayside.