Probably. There wouldn't be as many of them, though, and Sanders likely wouldn't have run against Warren.
Well for argument's sake, let us just assume that scenario did happen. In fact, it does not have to be Warren. Someone else respectable would also fit my question.
I'll expand on my earlier comment. I imagine that all insurgent campaigns attract insufferable supporters who make a lot of noise. Really, I think those people would act like that with Sanders running against any "establishment" figure.