NBA has proposed

• A new “Carmelo Rule” that would prevent teams — as the New York Knicks did in February with Anthony — from using a Bird exception to sign or extend a player acquired by trade unless they are acquired before July 1 of the final season of the player’s contract

• The abolition of sign-and-trades and the bi-annual exception worth $2 million

This rule wouldn't have prevented Melo forcing his way out, but it would have completely changed the dynamic.  It wouldn't have dragged on through half the season.  Melo always had the sign and trade option in his back pocket, so he always knew he wasn't at risk of losing his extension.  If this new rule is adopted, the teams will have a lot more leverage.  A guy can still get out of town if he wants to, but if the team doesn't get good value in return, they can force him to make a choice between staying for max money or leaving for a  substantial reduction.