Sort of like in 2016, you mean? When lots of Bernie supporters decided to vote for a third party, or just not vote?
Yeah, that will be disappointing, but not exactly unusual.
It happened in 2008, when Hillary's PUMA gang revolted against Obama. Luckily we won that one anyway.
I'll be voting for the Democratic nominee no matter who it is (assuming it is one of the current candidates, that is). Of course it doesn't really matter here in Oregon, but I hope Democrats in the swing states can do the same.
barfo