This is exactly what happened in California recently with Net Metering 3.0 -- the utilities cut the value of the electrons you export back onto the grid, and they even broke that value out into a supply chunk and a transmission & distribution (which effectively cuts the total export value even more because they argued that the marginal electron is worth a tiny amount as far as the t&d line items go).
What's happening in California is new rooftop solar doesn't pencil out unless you pair it with batteries (ie you self-consume all your excess), and even then it gets iffy.
There's also the trend where operators charge fixed costs for connectivity. So even if you self-consume everything, you still pay $15-$50/mo just for the connection. That gets trickier because it punishes low-usage users like apartment dwellers and small households because that looks the same as a solar house that self-consumes most of their electricity.
