I think you have it backwards here for the most part.

What problems do you see infinite blockchains solving?

No comment on whether or not a crash is inevitable, who knows where the price is going. That's not really too important to me. But the fact that Bitcoin is for now the most secure and technologically sound blockchain is what makes it interesting. And actually having those unique characteristics is what makes it special. I definitely don't see much special with 'blockchain the data structure' on its own.