Dare I ask, what happens to data brokers that don't care about Californian laws? Must be many such instances operating from outside the USA?
California will take them to court and/or block them from doing business in the state, have various ways to penalize them, etc. California is big enough that many will want to play game with them and having a state as powerful as California on board will get other states to jump on board and pass their own legislation and take up the same tactics with non-complying companies. Once it gets enough traction at the state level, the fed will step in because this will affect interstate commerce and that is federal jurisdiction. This is how state sovereignty works, it is not that states can do as they please, they can only do it up until the point it affects other states or crosses the line with federal law.
They open themselves up to a lot of risk, but more likely they only comply when CA residents are concerned or stop collecting for CA residents. Good question about outside the USA. Makes me wonder if there may end up being some sort of data broker safe havens setup, like we've seen with banking.