So no flights to atlanta
Delta done have that route (not sure the schedule) and the plans for BWEE flying that...so many people and company name changes since then it probably not a priority or even profitable any more.
CA could feasibley do Atlanta, as Delta only serves the route four times a week. The other thre days it comes to Piarco from JFK. Delta is on a massive expansion drive though. It is the only US airline in Arfica, and will be the first to Guyana soon. It also has a weekly flight between ATL and TAB (Tobago).
As far as CA, they would probably need to start acquiring more aircraft if they want to keep up. Back when the airport got downgraded, they (as BWEE) lost out on the opportunity to get a non-stop to Houston. Continental has had it and been doing well with it's daily.
I read that Spirit will be starting FLL-POS in June and American is adding a third daily to Miami. Should be good for travellers to the US with regard competition.