The problem Labour faces is the divide that Brexit has made all too evident within the party between its working class supporters from smaller towns (often in the north), and its metropolitan supporters in London et al. The two groups don't really have a great deal in common, and are especially divided on social issues (immigration, crime etc.). I can't see really how any party/leader can reconcile them, and they run the risk of the Lib Dems snapping up the metropolitan voters and UKIP snapping up the northern voters. That prospect has only been staved off to the extent it has because UKIP are even more chaotic than Labour are.