Times are different. 4X on JFK PTY could work. I don't think they intend to challenge CM.
By the end of 2007, DL started a venture to Central America out of New York City from JFK: GUA, PTY, SJO and LIR.
However, the mortgage crisis in 2008 stopped these flights as the jet-fuel rose to unsustanaible levels.
Given the recent incursion of B6 from JFK at GUA, SJO, LIR and SAP soon, DL would participate in that bulky market.
Bear in mind, DL JFK-SAL 7x weekly is actually in service and facing AV SAL-JFK 21x weekly.
The opening of DL JFK-PTY will face CM PTY-JFK 28x weekly who is leading this market.