Nuclear is ok for district heating because there aren't many alternatives. Burning gas 20% of the time as backup is not as big of a problem as many people make it out to be. The atmosphere doesn't care when you pollute, just how much, so intermittency is one of the biggest red herrings of all time.

If we had grids with 80% renewables you can start thinking about grid storage but right now it doesn't matter that much.