If California follows Washington's lead, the primaries next year will be fairly boring. The incumbent and an opposing party challenger will go to the general election. Even the one open race was boring, with three Republicans and two Democrats splitting the vote as expected. One of the objectives of this proposition is to produce more moderate winners, but there's no indication of that here.
How will California be different?
Prop. 14 proponents may have wanted the more moderate candidate to win, but that will only work if moderates on both sides of the aisle band together. If voters stick to their own party in the primary the more ideological candidate is still going to win. This is what happened in the CA-36 special election. Thus the choices didn't include moderates.
We also haven't had a situation where two incumbents have run against each other. In CA-44 Democrats expect to get around 80% of the vote, with the Republicans getting 20%. If Janice Hahn and Laura Richardson face off, they are very lucky to finish top two and face off in November. The big question, which Washington doesn't address, is how those 20% who usually vote Republican will vote. They are likely to be pivotal in deciding the winner and may go heavily for the more moderate candidate. Will they go after these voters with a different pitch? Will they alienate Democratic voters by trying to position themselves to Republicans?
Democrats Howard Berman and Brad Sherman will face off in the 30th district. In the 2010 gubernatorial election Jerry Brown won this district 57%-37%. If it's similar in the primary and Berman and Sherman are close, a Republican is likely to win. One of the two incumbents won't advance to the general election. If Berman and Sherman split the vote 30%-27%, Democrats will need one or more Republican candidates to steal 11% of the vote. That'd save them for the general election. If it were Berman and Sherman, Republicans would decide the November race, not just be a factor. If 2/3 of them flock to one candidate that candidate could lose Democratic voters 34%-25% and still win.
Here's another possibility that probably won't happen, but is possible. Here was the CA-36 Special Election primary results:
What if the top three Democrats were closer in their vote totals, but only two Republicans ran?
You'd have two Republican running in a general election in a district the Democrats are very likely to win in normal circumstances. There's nothing far-fetched about each of the factors in this scenario but, with 53 congressional districts, 40 senate districts, and 80 assembly districts it's certainly possible.