When Cuba agreed to allow the installation of Soviet missiles that could reach the US in less than ten minutes, they reached their own special "enemy status." The absolute worst thing imaginable would be to give Castro the chance to declare that after over 40 years of embargo he was able to "outlast" the US. We have made it very clear what is the necessary prerequisite for normalized relations with Cuba: Castro and his cronies have got to go.
Personally, although JFK implied we'd not try to invade again (either directly or by proxy) I think we need to break that ill advised promise. We know how to do it. As demonstrated in '03 in Iraq. And in this case, there would be no insurgents since they wouldn't be able to sneak in. If anything, the remaining Christians in Cuba would jump for joy upon being returned to a normal state of existence after the final waking from their 46 year long nightmare.