Yep. It’ll survive constitutional challenges, since there are already two states that do apportionment and if the voters amend the charter, there’s not much the courts can do (i.e., Proposition 13).
I notice that a similar measure in Colorado is supported by Democrats. I for one am tired of my vote not counting. It will be interesting in this next election if Hillary doesn’t carry California if the Demorats in Sacto will resurrect this issue.
Apportionment is certainly legal. However, the Constitution specifically gives authority to the Legislatures of each state. What has not been decided is whether direct vote of the populace is the same as actions by the Legislature.