New Labour was an electable project.
The point of a serious political party is to be in power to change things or it is a complete waste of time. Say what you like about Blair, his governments got things done.
What caused a problem for the future by Blair’s own admission was taking too much power from the members, understandable tho that was. Hence the pro-Corbyn backlash.
Whether Labour’s leader is Starmer or anyone else, without power it is pointless.
Labour’s chief problem is probably the way it is itself governed: the NEC needs to be reformed.
The other issue it has as I’ve said before is that currently the Tories under Johnson have stolen a few of its clothes, at least in the talking stakes. Unless and until that’s exposed as a sham then it will be difficult for Labour.