I don't feel like signing up for the report, but the summary is right that coal capacity factors have been declining. I've heard the term "death spiral," and I think it applies here. Coal is most economic at higher capacity factors and with multiple units at a single site. For example, a 2x500 MW plant might have been built assuming 80% capacity factors. Declining economics means it's dispatched less. Retiring one unit might raise a remaining unit's usage, but now you have maybe a third less staff but half as much income. This then kills the economics of the remaining unit.

What the summary doesn't address is why they think coal's experience will apply to nuclear and especially to hydro. Existing nuclear has a lot of cost to remain running, but it's all fixed cost. Nuclear is expensive to run, though (compared to wind and solar).

Hydro has lower fixed costs and zero fuel costs. I can't picture a scenario where new wind and solar is cheaper than existing hydro (unless it's substantially subsidized which it might be).

New wind and solar tend to hurt their own economics because if it's windy at one site, it's probably windy at all sites in a pretty large geographic area. Solar obviously has the same issue, including weather like clouds. Any solution like batteries or more transmission hurt the economics.

Gas has risk, though, I agree with that. Cheap gas is contingent on fracking staying economic. Lower oil production could drive higher cost for gas and push its usage lower.