I would assume he'll resign (or get fired if he refuses to resign). It's not like anyone can prove anything either way, the NBA's not gonna subpoena Twitter (which probably wouldn't cooperate) or seize Colangelo's phones and computers. But, man.
I gotta wonder what the dynamic is, if the league really forced the Colangelos on Harris, presumably he'll be happy to have the out. And Silver looks really bad.