Re: You can always count on the GOP!
"If the democrats were really smart, they'd sit out the next election and make sure republicans keep full control so they have no one to blame"
The US economy almost certainly will crash and burn, as you say it's cyclical but also Trump's presidency is accelerating the eventual nosedive with his short-termist tax cuts. It does not matter whether Democrats regain the house or not, now or later, or if Trump gets a second term or not, it will make no difference.
Fox will blame the Democrats for obstructionism (if they don't take the house / senate / presidency) and for incompetence if they do. Nothing bad that happens will be because of Trump or the Republicans enabling him. Republican voters will believe every word unquestioningly.