Per my friend that works at Delta, they have had Belize on their new route request list for sometime. But their getting access to that route has something to do with negotiating routes with other airlines (i.e., they have to let one of the main airlines that flys to Belize have access to one of Delta's prime routes or something of the like... something to do with airline route politics). I gather Delta has several caribbean and central american routes on their request list and have for some time, but it depends on the above. That has been a pain for me too as all my FF miles are on Delta. I managed to use them on Air Jamaica this year but then AJ got rid of its flights to BZE. I am keeping my fingers crossed this code share arrangement goes through and includes FF mileage redemption.
Right now we have to pick and choose our vaca spots cause the cost to get to Belize, Roatan or wherever is so pricey from Atlanta since Delta doesn't fly to any of them. If they do that'd make it a lot easier to get back to AC plus visit new spots!!! So keeping my fingers crossed still..... though its been 2 years at least since I heard Delta applyed for BZE access.
Andrea in Atlanta