Now, if Google+ did get dropped, which seems hard to believe based on all the integration it has across all of Google's properties, but if it is, how would that impact SEO and the search results?
Organically, we know Google+ has no impact on rankings outside of personalization, if any. We do also know that Google+ is a large part of powering authorship these days. We see faces, mostly pulled from a Google+ profile, all over the search results. We also know which of your friends like a URL or not, often.
If Google+ was dropped, Google would have to source the images from somewhere else, but likely would still be a Google profile. Google's rankings should have no concern or change based on Google+ dropping.
Matt Cutts was never a fan of Google+ being used for rankings, or any social network.
Forum discussion at WebmasterWorld.