I agree with the implication of your last question. It would certainly make sense for google to integrate Google Plus directly into their core product. I haven't thought of an exact path this would take, but if you're branding an operator, brand it everywhere.
Consistency cuts both ways. There is the branding consistency of the + symbol, and then there is the consistency of how + worked for searches last week vs. this week. My vote is that consistency in usage trumps consistency in branding.
Google+ probably gets much more usage than the + search operator. I'm sad that that part is becoming harder, but if they have a use for + that's integral for a future piece that relates to Google+, the needs of the many and all that.