They really could destroy the GOP if they actually said what their base wants to hear and did something to back it up, it wouldn't even be close but of course the dems aren't going to do that because the working class are far to the left of their corporate owners.
I'm not a Bernie bro but honestly I think Sanders would have won by a landslide even pulling in many republicans, but then his biggest opponent in power would be the DNC and media would be against him from day 1.