Sadly, numbers don’t work that way. They’ll lose a net of 3; maybe 2 depending on the outcome in Arizona.
The House is going to be razor close. I’ve looked at the races in play, and my best guess is that the D’s come out ahead at the end with a 3 to 5 vote majority in the House; a loss of 26-28 for the R’s.
If that turns out to be the case; it will be the slimy moves in PA and NC to force court-ordered congressional redistricting after those 2010 census maps had been in place for 3 election cycles (2012,2014 and 2016); that wins them the day. Once again, what the D’s would not have been able to secure at the ballot box, they would have stolen through the courts.
Your cynical assessment of the likely composition of the U.S. House strikes me as realistic. The only silver lining I see in this glum outlook is that two years of incessant leftist howling, extremist legislation, and malicious House Democrat investigations of every Republican under the sun will shock the country into returning control of the House to the Republicans in 2020. Naturally, Donald J. Trump himself will win reelection in a near landslide.
Admittedly, assuming slightly better Republican control of the Senate during this posited interregnum, I also see two more conservative Supreme Court justices attaining their seats, which would be rather more than a mere silver lining. All in all, the 2018—2020 period looks like an extremely noisy, hostile lull in the buildup to a historic 2020 decision on the soul of the United States.
Opinions on this event can and will vary.