LeBron will dethrone Dwight Howard as public enemy #1 if he goes back to the Cavs. People there won't forget the "betrayal", let alone forgive.
And Melo possibly going to the Lakers...I think that will pretty much mean that he'll never win a ring. All he'll have is the opportunity to rub elbows with more famous people, and more money. Lakers don't have a coach, let alone much of a roster that can contend for a championship. Even LeBron and Bosh have 2 more than Melo. I think Melo should instead consider joining the Chicago Bulls. It's a glamour city (he can expand his brand there), and he can play alongside a talented roster, as well as a renowned coach in Tom Thibodeau.