Well, nothing is fully clear about what will happen with the Northeast-Florida routes, as them being under 1750, they would normally not qualify for the Songesque mainline product, however, with B6 still on the routes, I doubt DL would really drop Song or Songlike mainline completely from these routes, as the product is already very well established. Also, you have to consider that not all Song 757s will be switched over to mainline asap. That process will take a few months. And of course, not all routes over 1750 actually will see 757s, but rather 738s or 763s, depending on the demand.
Again, everything still remains to be seen, but personally, I wouldn't worry about not having the Song product on the flight.