I don't think moving further to the left is a good strategy for the DNC especially since Clinton, even as a shitty candidate, would probably have won had it not been for those dirty tactics that alienated the Bernie supporters. If the Democrats move further to the left then they'll have no shot in retaking those districts that Trump won.
But we know what's going to happen in 2018 and 2020, they'll run "We'll stop Trump" or "Our candidate isn't Trump" ads down our throats and it'll be the same results as 2002 and 2004.