He probably would have won. I feel most of the backlash because of the debate was a manufactured snowball effect.
It's so easy for right-wingers to say, "I was going to vote for Biden, but not after that debate!" when they were going to vote for Trump all along.
I unfortunately don't think most left-wingers are autonomous enough to recognize this kind of behavior.
Pivoting to Kamala Harris of all people was perhaps the worst decision they could've made, and shows how out of touch the democratic establishment is with the working class.
Pivoting to Harris was the second worst decision they could have made. Sticking with Biden would have been the worst. His own polls showed him losing by even more than Harris did. You're dreaming.