I think that Trump will do anything to get out of a town hall debate. At this point, if he can't shout and scream at whoever is around him when he is supposed to answer questions, it's not gonna fly. (no pun intended)
But the optics of Biden fielding questions from voters and addressing their concerns all by himself while Trump refuses, is really, really bad.
Especially bad, is that this debate is the only one coming up that has the ability to make a difference. The last one is like 4 days before Nov 3rd.
By that time, unless Joe takes his old shrively dick out and pees on Trump's foot, shouting I LOVE WAFFLES, then this thing is done at that late date. Hell, even if he did that it would still probably be done.