Democrats actually grew their numbers in 2010 and then they fell back to their pre-2010 levels in 2014. I think that if Hogan wins by 52%+ he could knock off a few more Democrats down the ballot. I don't know how many the GOP would need, but I would think that one of the chambers is doable.
The only remotely plausible option, imo, is the State House, and Republicans would need a net gain of 7 seats to just barely break the Democrats' supermajority.
Reducing Democrats to their smallest State House majority in over 80 years during a midterm of a most likely unpopular Trump presidency is a hell of an undertaking. It won't happen. My guess is that Democrats gain, as opinions of the incumbent president's party heavily influence state legislative races.
I think Hogan will probably win if he is still really popular, but more gains in the legislature seems highly unlikely.