I'm definitely now starting to think that Labour need BJ to stay, to improve their chances of winning/ getting a coalition. If I was a Labour strategist I think I would think about taking the foot off the gas a little now, no point shooting a guy when he's already dead. Unless they think they can pummel them down to an unrecoverable level, which certainly looks possible.
But I think Tory tactics are probably going to mean a leadership change in the run up to the GE. I think this change will come after we're over Omicron (which is probably going to be the end of Covid for us) and heading into summer. My bet is they've discussed it with BJ already, and he gets a hefty pay off to continue to take the hit (most of his own doing), until they get near their perceived lowest level of support, then he goes then. Then they go for the "new manager bounce" at the time of the better mood in the UK (summer). Then they'll start on the gravy train of false promises and lies with the new guy.
It will give them 2 years to build up the name for the new guy and they will blame all their failings on BJ (and Corby/ Starmer of course).