I don't see that this is a major socialism scare, because it has happened before for ordinary political reasons. Sometimes these incumbents take their voters way too much for granted and the voters rebel.
Just a few years ago, in a major upset, House Majority Leader Eric Cantor was defeated in a Virginia primary by tea party candidate and political novice Dave Brat. Cantor didn't bother to show up or run, really ---- why should he? He was an important person, the House Majority Leader!!
Same thing in New York. Wait and see if she wins the real election and has staying power before worrying about socialism, I'd say, though I don't like it either.