Of course this isn't going to convince diehard Trump fans, but he's already doing bad with women voters, who are absolutely essential if he wants to win, and this definitely didn't improve his chances. If Sunday goes anything more than disastrous for Clinton (which unless Trump magically started learning how to prepare for a debate shouldn't be a problem), her campaign will start focusing on critical senate races. Trump simply doesn't have enough time to regain the ground he lost after the first debate.
Odds aside, from a European perspective it is absolutely mind-boggling how a clown like Trump got past the primaries. His policy positions are awful and exactly zero of the made up charges against Clinton (Foundation, emails, Benghazi, BILL IS A RAPIST!!!11!) have turned up anything substantial. Thank fucking God we're unlikely to have to deal with a POTUS who thinks NATO is a protection racket and that trade surplus is the central issue for economic policy.