Restrictions between Mexico and US flights set to end. Hopefully this means that airlines will add frequency's to Cancun or add other Mexican destinations from logan.
http://www.reuters.com/article/us-mexico-airlines-idUSKCN10W0OE
The only thing tapped out in Boston per the old bilateral was the amount of USA Carriers that serve Cancun as scheduled service. See below for a link to the post concerning the high amount of 1-stops on Boston-Cancun. You could say its underserved from Boston but is it worth it chasing the low yielding passengers.
http://www.archboston.org/community/showpost.php?p=268947&postcount=3030