Those who would benefit from its repeal - renters, people who moved out, people who choose not to move to CA in the first place because of cost and governance, children, etc, either don't vote as consistently or can't vote in CA at all.
Proposition 15 (which would have eliminated commercial property tax breaks) failed 48%-52%. I think its biggest political flaw is probably the fact that it would apply July 1, 2022, with no phase-in for small businesses whose lease passes through the property tax. So hopefully in November 2022 another attempt can be made that addresses the political shortcomings.
Proposition 19 (which eliminated tax breaks for inherited investment property in exchange for increased tax portability for the elderly) only barely passed 51%-49%, and that was after it received overwhelming support from the legislature, and a $45 million advertising campaign from the California Association of Realtors that some people criticized for only highlighting the goodies for old people and not the costs for inheritors.
No one is attempting a full repeal of Proposition 13 including residential property.
It could also be attacked judicially; see this episode of the Henry George Program for a discussion of Nordlinger v Hahn and whether different legal arguments could be tried (e.g. does Proposition 13 impinge on the American freedom to migrate under the US Constitution?) http://seethecat.org/ep/2017-07-11.html
I believe it could be revisited on the grounds that Prop 13 primarily benefits white families (makes sense -- they were the only ones buying property 40 years ago).
There is now good data on the racial disparities in our current tax law and with enough money I think another lawsuit has a chance.
https://twitter.com/alfred_twu/status/1327821019931787264?s=...