I'd have more faith in Sunak staying if he categorically promised he was going to California.
The Tories have basically slashed'n'burned their own core vote. This is what happens when you take them for granted. And a mass awakening isn't something you can wave away with some cheesy soundbite.
Given there's a cycle in politics, maybe it turns when the "core vote" suddenly realised that they are bottom of the queue for everything from their party of choice. After all, if someone is happy to announce to the world they "always vote Tory" then why in Gods name would you do anything to buy that vote ? I know I wouldn't. I'd take that free vote (cheers dear) and actually spend my money on people who weren't going to vote for me. Which is basically the last 14 years.