That's my gut feeling.
I don't think it's at all impossible for Biden to win, but that's my gut feeling.
To be more specific: I think the "Red Mirage" scenario will happen. Trump will have a lead on election night and he and the Republicans will pull some fuckery to stop mail-ins from being counted in the right places.
If it gets to the Supreme Court, either Biden and the Dems will pull a Gore and surrender the election without a fight, or the Court will rule in his favor and hand him victory.
History will repeat itself.
Either way, he won't give up without throwing a pissy fit to rally his cult though.