I am waiting for either:
1) The labour party to remain hard left controlled and move to being a fully hard left party by, possibly, electing RLB and continuing the purge of moderates. This would likely lead to 50-150 current labour MPs leaving to form or join a centre left or centre party. This might get our militant moderate movement going even though one might have some reservations about the likely quality of the people involved given their track record for the last decade or two. We might get a libdem's mark 2 playing to the gallery.
2) The labour party returning to a moderate (electable) position and disempowering the hard left. This is what a number of people seem to be expecting if, for example, Starmer is elected. My suspicion is that the hard left will refuse to get back in their box and will possess enough power to resist at least for a while. Labour would then continue it's internal conflict and a starring role in an ineffective opposition. Perhaps things will get resolved and perhaps not. They would stand a good chance of being elected next time if social and economic conditions fall sufficiently as seems likely. I wouldn't have high expectations for a militant moderate movement lead by labour but the possibility would still exist.
The radicalisation of moderates is not easy. A negative way for it to occur might be if social and economic conditions seriously fall which is a possibility if a hard brexit is combined with a significant loss in confidence in the UK by the rest of the world. A positive way might be the appearance of a decent leader/movement talking openly and truthfully about the UK's current situation and how to move forward in a balanced way. The key here would be winning the trust of both the working population and the wealth generating component of capital. Not one or the other but both. Opposition from those benefiting excessively from the current setup will be inevitable as it will be from those on the hard left and right. It could come from labour, the libdems or from outside but at the moment there isn't even a hint of it that I can see. Let's hope I am just useless at looking and the militant moderates really are out there getting their act together.