Firstly, the current problem is not all future problems. Bots spray Twitter with insane volumes of low quality spam because that requires the least possible effort. But it’s not to say that is all they can do. If user verification made mass spam less viable, they’d pivot to more targeted alternatives.
I actually don’t think verification will even combat spam at all. Firstly, the kind of users falling for these scams are likely not thinking critically in the first place (a website that doubles your bitcoin? really?). But more importantly, I think it’s unlikely enough people will pay for verification that users will start to see unverified accounts as less trustworthy.
In fact, giving the option to boost accounts visibility could open the door to more problems. Scammers, spammers, and bots need only exceed $8/month worth of value from an account for verification to be worth the cost. Social media verification has always given an illusion of trustworthiness. it could certainly be worthwhile for bad actors to pivot to more convincing messages from verified accounts, rather than carpet bombing with burner ones.
Give that state-backed disinformation ops have always been a cost center, I can’t see any real effect there. In fact, being able to buy verification (even if the account gets banned after a week) would be highly beneficial. 1000 verified accounts for $8,000 a month is simply a rounding error for an influence op.