I'm not sure why the Cornish branches seem to keep coming up - they are probably economically about the best a branch line can get because they're full of tourists, at least in summer.
The other ones are possibly it, yes.
I do wonder about the Conwy Valley if, given that I've spent some time cycling old railway routes during this COVID thing (did Bridgnorth to Ironbridge yesterday), it might actually be more use as a cycle route, ideally properly tarmacced, with the money spent on an hourly clockface Trawscambria route. That said, for most of its length there are parallel minor roads, you don't have to ride on the main road. But I think Wales thinks differently, and so I would be surprised if it was axed - if it was still under English remit, I'd be surprised if it *wasn't*.