What if Democrats win House popular vote in a landslide but GOP keeps majority?

[Pericles]

I was playing around with the 2016 House results and I decided to see what would happen if there was a 6% swing from the Republicans to Democrats, so all races the Republicans won by 12% or less go Democratic. The results were terrifying.
2016 House elections
Paul Ryan-Republican: 222-25 43.1%
Nancy Pelosi-Democratic: 213+25 54.0%
Martha Roby loses
Jeff Denham loses
Steve Knight loses
Darrell Issa loses
Mike Coffman loses
Carlos Curbelo loses
Ileana Ros-Lehtinen loses
Rod Blum loses
Kevin Yonder loses
Jason Lewis loses
Don Bacon loses
Leonard Lance loses
John Faso loses
Claudia Tenney loses
Brian Fitzpatrick loses
Lloyd Smucker loses
Will Hurd loses
Barbara Comstock loses

Please note these are alternate 2016 results not a prediction at the 2018 results. 2018 will have different races and could be different. However, even if both Osoff and Quist win and retain their seats in the 2018 elections the GOP will still have 220 House seats. Please correct me if I missed anyone. These results as the 2018 elections:
2018 House elections
Paul Ryan-Republican: 222-19 43.1%
Nancy Pelosi-Democratic: 213+19 54.0%
435 seats
218 for majority

I was astonished how much the Republicans can afford to lose by and still win. I realized of course that gerrymandering was a problem but I thought that if the Democrats win by margins in the high single digits or higher they could overcome it. But not even an 11-point Democrat popular vote win would have overcome gerrymandering in 2016. Donald Trump was right, the system is rigged. This outcome is a giant middle finger to democracy. If an outcome like this occurred IOTL, it would give me (added) reason to fear for the health of America's democracy and its institutions and public trust in them.

What do you think would be the effects of such a result in the 2018 midterm elections? What would be the reaction to Democrats winning the popular vote by double digits yet still being denied a majority in the House? How much, if at all, would US democracy be hurt by such an outcome? How would this affect the rest of Trump's presidency(presuming he is still President)? How would the 2020 elections be affected? What if?

[Person Man]

It would probably have the same effect that the Dred Scott decision had on our country. I mean, wouldn't it?

Although, most likely, a 7 point win that flips the house is still more likely because Democrats will campaign harder in R+5ish seats with Trump-lite candidates running against Trump the way Howard Dean did in 2006 against Bush.

[Heisenberg]

Martha Roby nearly losing was a fluke due to a strong write-in effort to help her defeated primary opponent.

[Hindsight was 2020]

Dems will freak, Trumpers will yell "suck it cucks", an it becomes the topic of a documentary by the BBC

[RINO Tom]

It will be an even clearer call that Democrats can't rely on majority-minority rural counties, diverse inner suburbs and diverse cities to have any power...?

[rob in cal]

  One reason unfair results like this might not have as much resonance as they should have is that on election night the media organizations don't total up percentage of vote and compare with percentage of seats like they do in Canada or the UK.  So any unfair discrepancies due to gerrymandering and amassing huge results in urban areas is lost in the overall political chatter.
   Suggestion for Dems.  Get behind proportional representation both in states where you might not benefit from it (California) and in states where you would (Michigan and Ohio).  Even if you couldn't get it passed for congressional seats, having PR in place for state legislature seats in places like Michigan and Ohio and Pennsylvania would guarantee that Dems would have a fighting chance for a seat at the table come redistricting time for congressional seats.
   

[Virginiá]

It would sure be a big indictment on the way we conduct elections. It basically means the US House and many state legislatures at that are no longer serving their actual purpose. It would be in the best interests of everyone if both parties worked together to make elections more responsive to the people, because eventually Republicans will lose their grip, even if just briefly, and Democrats could move to unilaterally fix what they perceive as injustices in ways that perhaps unfairly hurt Republicans.

The biggest fools in politics are the politicians who act like they will be in power forever.

[rbt48]

OK, I'll bite.  How is it different than the 2012 House results (except for the magnitude of the popular vote margin)?  The GOP retained a 234 to 201 margin but lost the popular vote.

Separate related subject: 
(1) How is the popular vote counted in uncontested (or minor party only) races? 
(2) Jungle primary states with D-D or R-R elections give "artificial" benefit to the party that makes it to the general election.  Do  the non-participating parties get any vote credit in these districts?

[RI]

The national House popular vote is even more meaningless than the Presidential popular vote.

[CapoteMonster]

If they lost the popular vote by 12, there's no way they'd keep the house. The last times dems did that in 82 and 08 they won around 260 house seats.

[Adam Griffin]

Then the need for a political revolution in this country will morph into the need for an actual one. Because irrespective of CA or whatever, it will be both indicative of an institutionally-rigged outcome and the topping on the cake of a much broader problem that can't be corrected by votes alone.