I think the end of the Labour party in its present form is devoutly to be wished for.
Over a very long time it has been riven by factionalism and you never know who is going to run it from one day to the next.
It is one of the reasons many people, including myself have never voted for it. If I vote for a party, I want to know I am voting for the one in charge when I vote for them.
I think there would be much to gain from a left of centre party and a left wing party, with clear agendas. The two would be greater than the whole, as many, from both ends of the left would be able to vote with confidence for a party that supported the principles they espoused. Not one that veers from one to the other at regular intervals.
Each party could present the electorate with a clear agenda that they could support or not. I think both would attract new votes.