Sadly competing with coal and natural gas on cost is relevant. I think we should close those plants as soon as possible even if it means replacing them with a more expensive option, but sometimes it's hard to get political traction on things that cost more. Solar and wind tends to be cheaper than fossil fuels, anyways, though that might not be true if you have to factor in batteries. (Whether that's an issue is geography-dependent: I'm in Oregon, and we get a lot of our power from hydroelectric, which means we can use bodies of water essentially as capacitors to buffer out the irregularities in wind and solar. The East coast doesn't really have that option.)

I don't mean to be hostile, I'm just saying that as far as I understand it, nuclear is expensive which means that people who are looking to get the most power for the least cost probably are going to go with wind and solar. If we can somehow make nuclear cost competitive then that's great but I don't know what's needed for that to happen and in the mean time I think the sensible thing is to treat nuclear as something that might work, but we aren't counting on it.