I think Trump is somewhat like Perot.

He's unquestionably highly accomplished in business, and while probably not as skilled at negotiation and consensus-building that someone needs to be a political leader or president, is a heck of a lot of fun to listen to, and offers a valued opinion to political discussion.

I still love the way he got Obama to reveal his birth certificate, when no one else could, and how he hurt Obama's popularity numbers.
Trump might not be a good leader, but he is a pretty good campaigner, and that he sqeezed that concession out of Obama is testament to Obama being scared of what Trump can do.

Trump hasn't gone away, and though not a candidate, he can rally support the way Palin and others have.