It's hard to see how it will all play out, but Republicans shouldn't think that unified control and big downballot success right now means they have solid footing going into the future. Democrats probably thought the same in 1992/2008, and yet everything changed 2 years later.
But that's a much more mild statement than what you seemed to be hinting at in the rest of your post.
Yes, any electoral victory is fragile. It can be reversed quickly, and a victory today doesn't preclude a defeat tomorrow.
But any reasonably informed political observer knows that. The more provocative question, which is I think what the thread is supposed to be about, is whether the next reversal of fortunes won't be just another cycle in the back-and-forth of American politics, but a precursor to the Dems having some kind of growing structural advantage due to demographic changes.
That is, is it just that the Republicans shouldn't think that they "have solid footing going into the future" based on their current victory, because no victory indicates "solid footing"? Or is it that it's the Dems who have solid footing going into the future, and the '16 presidential election was just a hiccup?
