There will be elevated Republican turn-out
We've seen it in past primaries and we're seeing it in the absentee voting. The chart below shows it a little simpler.
So far 11.2% of Democrats have voted, and overall 11.1% of the state has voted. That indicates that, comparatively, Democrats aren't experiencing low turn-out. Republicans have had high turn-out so far, while independents and third party members have had low turn-out. I'd guess that as more independents learn about Top Two the turn-out will be higher. Just not this year.
Republicans vote Republican
Exit polls in California show that regardless of turn-out or independent vote, 85%+ of each party will vote for their own party. We've had a mass exodus from both parties, so those that are left must like their party. In 2010 5.1% of the votes were for the American Independent candidate in CA-11.He had no realistic shot at winning and had they voted for the Republican or the Democrat they could've swayed the election.
This isn't to say that some people won't defect in a race where the other party is sure to win. It should just be a small number. No matter how hard you try most Republicans won't vote for a Democrat.
Independents aren't monolithic like Republicans and Democrats
OCPolitical has a link where they speculate which NPP candidates will advance. They say this:
Democrats make up 47.3% of CD-19′s registered voters, Republicans 22.6%, and NPPs are 26.3%. With the Republican vote split two ways and NPP voters already outnumbering Republicans, it’s likely that Cabrera advances to November, where he’ll be stomped by incumbent Lofgren.There are a few things they're missing. While the breakdown in the district is 47%D/23%R/30%Other, ballot returns are 50%D/27%R/23%other. So right away there are less independents and third party voters than he's assuming. Even more important is that independent doesn't necessarily equal moderate. Independents range in ideology from far right to far left and they can have party loyalty. Being an independent doesn't mean you aren't going to vote Democratic or Republican each time. It just means you don't want to affiliated with a party for whatever reason.
Likewise an NPP candidate isn't necessarily moderate. He or she, like the voter, decided there was good reason to go NPP, even if they're solidly on the right or left.
There are independents that are swing voters. That doesn't mean they're looking to swing to an independent, however. While some independents like third parties, others feel it's a wasted vote. Since independent doesn't mean a fixed ideology, who's to say they agree with the independent more than the Democrat or Republican?
There are some NPP candidates who do have a shot, but how a good a shot depends on the candidate. For NPP candidates having a certain party affiliation doesn't automatically get them votes.