The grid would not collapse but instead would evolve (maybe wiping out whole swatches of companies and utilities in the process but so what).

Many people won't (or can't) install their own PV/storage, but everyone needs electricity.

Those without PV and/or storage will need to purchase their electricity from others.

The mechanism for getting the electricity from seller to purchaser will be a grid of some sort.

La plus ca change and all that.