I really think that will depend on who wins mid-terms. If the Democrats win, I think Trump will get another four years. If the Republicans win, the Democrats will be against another "anyone but..." situation like it was in 2008. The reason I do not think that will happen if the Dems win mid-terms is because I think many voters will be hesitant about giving one party that much power.
In the long run, the Democrats need to loose, very badly, during the mid-terms, launch their own populace movement that makes the Tea Party and Trump supporters combined look as energetic as a corpse, and storm Congress in 2020 (under this scenario, it won't even matter who wins the presidency) so they can redistrict. Then, if the Dems have any brains, they will reverse the situation and make it very difficult for Republicans to get back in power in the House. Then, by 2024 when Millennials become the majority voting demograph and with more Boomers and old people having died, the way should be paved for Leftist social policy.