I do see some danger here: an energized base of Democrats could achieve historic gains in the House in 2018. But, I think they will have trouble holding on to their current position in the Senate, with so many Democrats up for re-election in red states.
If Trump sticks to his economic and immigration agenda, it will mute a lot of the opposition -- as long as the economy doesn't tank in the next two years. A couple of years of solid growth in the GDP will do wonders.
If Trump voters don't get complacent and make the effort to vote in 2018, it will hold the Democrats gain to a minimum. What will be interesting: if the leftist media goes "full retard" against Trump, will it energize conservatives to react as they did in 2016?
Holy Schneike, an honest Dem!