I used to work in VC. Although I've never deal with this situation myself, I've talked to other founders who've had similar experiences.

The general thinking is that the new team is essentially a new business. This new business needs cash, and taking that away is more or less a non-starter at this point. Fundamentally, founders are compensated for seeing things through, not for partial work. It's a really hard sell to either ask a cash-poor company for cash for non-productive purposes or to ask new investors to put up cash that's going towards an exit-package (ie. someone who's not going to be contributing). The only leverage you may have is how much pain you can cause by not being bought out, which puts you in an adversarial relationship with everyone else. I don't think that's good for you.

So I'd recommend you'd just hold on to your vested shares to build good will. Indicate your intent to exit, but you like the new idea and wouldn't put additional pressure on the business at this stage. If the business is successful in the future, you may get bought out by later stage investors to simplify the cap table and reduce governance complexity. But for that outcome, you'd need to be on good terms with current investors and the new team.