Current guess from my Bluesky feed is that the dancing on Starmer's grave is premature. The enthusiastic jiving is obviously coming from the RW press who are desperate to get a scalp, along with those on the left who see Starmer as a RW plant.
I think it's more likely that he weathers the current storm (possibly by jettisoning McSweeney as the sacrificial lamb to appease the non-Blue Labour MPs), but if he's going to go, it'll be after disastrous local election results, particularly if he doesn't take the opportunity provided by the crisis to change tack away from the McSweeney messaging.