I don't think GOP is throwing away the suburbs (at least I hope not) I think this has been "the 2 years of the pissed off women with education", starting with the marches, the pink hats, metoo, and Kavanaugh, and of course absolute loathing of Trump.
They aren't throwing the suburbs away on purpose. They're making their brand toxic to them by acting like goofballs (or attaching themselves to a goofball) instead of serious adults. No, that shouldn't matter, but for enough people it does. Many of these House districts went solidly for the last non-goofball Republican presidential nominee.
These women have been chomping at the bit to unleash their mighty anger toward Trump, and white men, and Republicans for a long time. Payback for Hillary.
I'm sure there's plenty of this, but guys like Pete Sessions in Dallas and John Culberson in Houston didn't lose because the bra-burning, pink-hat-wearing man-haters suddenly decided to ditch them. What sank them is that significant numbers of educated voters decided to vote with the man-haters rather than with the GOP like that those folks used to. We need to figure out how to recapture that demographic. Remember, these aren't swing districts. Many of these are districts that were solidly Republican just a term or two ago. Will some of these flip back in 2020? Some probably will, but the fact that these are even close is worrisome.
On the other hand, as current college aged kids grow up, and teach their kids their "values" I foresee a very different political landscape in a couple of generations.
It's well on its way now. Massive numbers of children have had checked out parents while they sat through 12 years of socialist propaganda in school plus whatever nonsense they heard in college. We didn't have to let that happen. We chose to with inaction and passivity. While the Right was caught up in tax cuts and making money, the Left was taking over college campuses, school boards, and media outlets. Let that happen for 40 years, and it's going to have a major cultural and political impact.