This year we fly down to SXM from JFK on 12/12. I have a price point where I will book the flights. Usually since AA comes out first with their schedule and they hit my price point I book with them. It's always N/S. Last year when JetBlue first came out, they beat the AA fare by $73 per ticket (Times 2 = $146 total). This year I waited for JB to come out with their fares because the AA fares were just a little bit higher than my price point. I'm very glad I did. JB had a fare less than I've ever paid and the departure time was civilized but not really late. I even got a small voucher for a future flight because the fare went down slightly a few days later. I learned of the cancellation of the N/S flight from JFK a few days ago and that made me even happier that I booked with JB. Other advantages are that JB has a little bit more legroom and as of my booking, the first bag is still free.
I don't understand why AA cancelled the N/S to SXM since that flight was always full. Anyway if it was AA's job to make JB the airline of choice to SXM, then they were highly successful.