But I saw a story online today that says that Frontier is supposed to start flying from SAN JUAN to SXM, starting in June. There were a bunch of other routes announced but the one regarding SXM was as follows:

"SJU to Saint Martin's Princess Juliana International Airport (SXM): starts June 3, operates twice weekly (pending government approval)"

Perhaps that will be helpful to some, as SJU has been pretty easy to get to in the past, but it has become very difficult to get from SJU to SXM, especially since AA pulled out of SJU.