Again, that is incorrect. Many of those district went for HRC in 2016, sometimes by large amounts. And we were gerrymandered out of 3 seats in PA and possibly a handful in a few other states. The house could easily be +15R to +10Ds with where things sit now and 2% turnout delta could easily make or break it.
And the Democrats are complaining about the Gerrymandering losing them seats.
There are also a number of Democrat seats that the GOP may flip to make up for those 3 seats. The fact is that the Democrats need to pick up 23 GOP held seats, which would take a wave election like they had in 2006. It isn't going to happen when they are losing Senate seats.