I will say though, there are people who purposefully get the circular. I once had someone at Downhill get on my 4, but only after I told her I hadn't seen the 136, and there's a fair few people go to Castletown on the 135 from that club on Clacton Road where the 3 terminates (couple times I've been on a backshift on the 3 and someone's been waiting for the circular). I think instead of just withdrawing the full thing, it might be best having it do the north estates and terminate at the turning circle on Grange Road. No idea what it'd be like timetable wise though.
I wouldn't think any cuts in service on stagecoach routes would affect nighttime buses - we have enough drivers for them and the service is pretty bare bones anyway.
RE: Go North East March 2023 changes