I wouldn't count on that since DL has the ATL hub plus most of their operations at FLL are from Song.
Only 17 of Delta's 60+ daily FLL
flights are operated by Song. That is less than 30% of Delta's FLL
services. Delta operates almost as many daily FLL
flights as all of Song's FLL
Delta actually was looking at starting FLL
prior to September 2001, though the plans were axed.
I would not expect Delta to start the route, but never say never. There is a lot of profit potential on the route. The market between Miami and Paris is very profitable thanks to a lot of high-yielding leisure traffic and the Miami-Fort Lauderdale area's large French population, which is very wealthy and travels between SoFla and France often.
The problem would be that Miami is still considered "the" European gateway, so it's they would have to advertise the service well. About a year ago, there was a new French airline proposing trans-Atlantic service from Nice. Their two US destinations were to be Newark and Fort Lauderdale. The airline never flew (no surprise), but it shows how important the market between the area and France is.