These are all good points, and well taken.
Having solicited feedback about the post, I think #1 and #3 in your comment reflects the part of my argument I could do a better job on. As a few others have pointed out, we can probably retire coal much faster than I imply. I do stand by the fact (as you allude to regarding government intervention) that actually shutting down those coal plants is politically troublesome enough that, while I may be dead wrong about the reliability piece, it is still unlikely to happen.
On the other hand, I have also spent more time with the projections and analyzing the capacity factors- and I think that if I were to rewrite (or add) to my argument I would do it this way:
1) We are adding 100GW of natural gas capacity by 2030
2) Projected capacity factors are staying constant, at ~25-30%
3) As coal goes offline (which it has to if we want to hit climate targets, as you note) what is more likely to happen, that we ramp up existing natural gas capacity (from 30% to 70%, or whatever is needed to maintain a capacity margin buffer) or that we build new renewables?
I think that we should just be aware of the dangers of setting ourselves up for that situation later on. I agree that natural gas (plus some EPA regs) have made the construction of new coal obsolete, and that is a great thing. But looking ahead, natural gas really can't constitute more that 35% (tops) of our energy supply in 2030, so lets not create the kinds of hurdles I mention in point (3) here.
That all said- your #2 point is well taken. I rarely give CCS and natural gas explicit credit- and I am open minded to that. I think we view it similarly (although I may be misreading you) that natural gas::CCS as renewables::storage. It is a supporting technology that changes the role that resource will play in the energy mix- and it shouldn't be counted out. But we can still make projections based on current technology and then leave the door open for those kinds of changes. It important to outline the risks and be realistic about what influences decisions down the road.
Thanks for reading, and for your thoughtful comments.