I wouldn't be so confident especially if you replace complacent with competence. The way candidates are elected will expose the dems and probably open wounds. You are then going up against a president who all normal conventions don't apply (but will still apply to whomever the dems pick). The president has Fox, most talk radio and most local papers backing him. The GoP elites might hate him but they won't dump him.
Trump will need the midterms to go his way, as he can't even get the votes when the GoP controls both houses. He also has to hope the financial bubble doesn't burst on his watch (its likely to happen soon regardless of who's in the White House).