Really, the D's need to get state legislatures and state governorships more than grab either House currently. With Trump in the White House, a change in the House won't be as important as being able to redistrict on their terms, or at least not GOP terms, for 2022-2030. That was where the R's took the D's to the woodshed 2010 and subsequently propped themselves up to survive 2012, hold on 2014 and 2016.
Trump and Congress wasting a lot of time trying to come to agreements takes some of the issues away that one-party rule often begets, especially if the gap is tight in both houses. A 50/50 Senate should be seen as a win even though it leaves the GOP in charge because it means they can't lose a vote. Plus McCain is essentially a non-seat voting-wise, only for control.