You have days, or even weeks where solar in the northeast is basically producing no power, so you still have to maintain a similar amount of non-solar generation as you have now. Batteries are a good bridge for the time-shift problem (peak demand, is often well before/after solar's peak output for the day), but it's unlikely we're going to build absurd quantities of batteries to handle a week of low output when a major storm moves through.

So your traditional generation will not run anywhere near as much in the past, but still has to be maintained and ready to operate. While some portion of maintenance costs are related to how often it runs ("this thing needs replacement every XXX hours of operation"), some portion are just for keeping the thing ready to run even if it's only used once a year.

The same also applies to the grid itself - when that solar isn't outputting for days, your house will draw the same power as if you didn't have solar, so the grid has to remain built out and ready to provide the same capacity to everyone as before.

How you allocate these costs fairly gets thorny.

For fairness, you'll probably see a somewhat higher share of your bills priced at a flat rate in the long run rather than per kWH/by usage.

Total bills paid by the population should be lower, but bills for a current solar owner might be somewhat higher.

I don't think this will kill the value proposition of home solar (especially with further cost declines/tech improvements), but it'll be a little less favorable in that sense.