This notion that eventually the GOP will come to their senses and switch from Trump to someone "sensible" is predicated on what, exactly? As far as I can tell, they've gone completely off the deep end, and there isn't anyone with enough balls to pull them out besides maybe Kasich, who's got no support. Trump's campaign has (inadvertently?) exposed the party as being comprised of exactly the bigoted assholes we pretty much always knew they were - and most of their base is fed up with trying to appear like anything different than that. They wear their bigotry with pride, amping themselves up in online echo chambers, lined with fellow sociopathic dipshits. The GOP is a once great, but now leaderless party in a tailspin, and they would much rather drag us all down along with them into oblivion than admit defeat. They're done, and any hope of them being reasonable, such as electing a sensible moderate, is long gone.
EDIT: I'm talking about the GOP nationally, not locally, of course. They are absolutely dominating the scene on the state and municipal level because the Democrats can't be bothered to take local races seriously.