I imagine his goal would be to speak directly to the Bernie supporters and woo them over to the GOP.
I get that, but I think it would be extraordinarily tough to do because Bernie would be right there to tell all his supporters exactly why they
shouldn't support Trump. It's pretty much the highest profile event Bernie could ever get in which to make the case how bad Trump is. And Trump would be forced to counter that by making himself appear closer to Bernie, which then leads to....
It would also showcase the difference between Free Market and Communism. If anybody can teach the ignorant Bernie bots why socialism is bad for them its Trump.
And that's the problem. I think you'd have to be an incredibly persuasive and adept speaker to navigate the minefield of wooing Bernie's supporters while at the same time convincing them how completely f'd up their worldview is. That's an awful lot to put on
any speaker in a debate (because really, how often do the minds of partisans get changed by debates?). I mean, maybe Reagan could do it, or maybe someone like Rubio. I'm not slamming Trump by saying he's not up to it because I don't think 95% of speakers could do it either.
Just think about it -- Bernie is going to get them all jazzed up about civil rights, and free health care, and college, and women's issues, and racism, and immigration, and the opportunity to make a complete, convincing case for capitalism is going to be small. I think the most likely result is that Bernie supporters will come out of there absolutely committed to voting against Trump, because that's the drum Bernie's going to be banging the entire debate. Remember, he believes he's a better candidate than Hillary in part because he does better against Trump. So he's going to be on the absolute warpath and drawing every distinction possible. And for some of it -- like comments about women, etc.., Trump can't counter Bernie as easily as he can counter Hillary because Bernie isn't the moral scumbag she is.