// Just watch those former Labour seats Boris won disappear next time around.//
They very probably will, although it's never going to be entirely clear how much that has to do with Johnson being removed as leader.
// Those people didn't vote Conservative - they voted Boris ... //
This I think is fair to an extent, *but* they also voted against Corbyn, and perhaps for Brexit generally. Who knows how things would have played out with a different Labour leader, but it's pretty clear that Corbynist Labour was doomed in 2019. But in any case, that was (almost) four years ago, and since then (and particularly since the back of 2021) Johnson has lost a lot of his support and popularity.
// and they've been let down - badly. //
That I agree with.