i could see formal verification become a key part of "the prompt is the code" so that as versions bump and so on, you can have an llm cpmpletely regenerate the code from scratch-ish and be sure that the spec is still followed
but i dont think people will suddenly gravitate towards using them because they're cheaper to write - bugs of the form "we had no idea this sould be considered" is way more common than "we wrote code that didnt do what we wanted it to"
an alternative guess for LLMs and formal verification is that systems where formal verification is a natural fit - putting code in places that are hard to update and have well known conditions, will move faster.
i could also see agent tools embedding in formal methods proofs into their tooling, so they write both the code and the spec at the same time, with the spec acting as memory. that kinda ties into the recent post about "why not have the LLM write machine code?"