What a mess. It seems like the fundamental issue here is allowing the grandfathering of old NEM rate structures, much like CA allows folks to grandfather in their old property taxes while screwing over new purchasers. Nobody should expect rate certainty for 20 years into the future, that's just an absurdly long time period to expect guaranteed rate structures.
It's not that complicated at a high level really - when nobody has solar, full net metering is reasonably fair. When everyone has solar, the whole scheme collapses because production doesn't align with usage exactly. So every few years during a rate case, they should all work together and shift the value of solar generation accordingly (likely downward). Folks need to take on a little risk with their major purchases because anything else is even more unfair to early and later adopters. The time value of solar production varies year to year and solar owners should be compensated accordingly. Batteries will bring value back to solar by allowing for load shifting, and much like solar, can be done by individuals or utilities.
Obviously the specific details are muddy as hell and will be contentious, but that's normal and reasonable compromises usually prevail.
The reality is some east facing panels in LA aren't that valuable these days. And the person with east facing panels from 5 years ago shouldn't get massive long term benefits locked in because they did the install earlier.
I live in Colorado, have solar, and fully expect the value of my generation to reduce over time. Expecting full retail value of my excess June production to offset power I badly need in Jan to run my heat pump simply isn't fair.