My family booked our trip back in November for going in August. I called our local TA and asked her if we were eligible for the free dining. She was able to get the information us yesterday, since that's when the promation went to the people without Disney Visa cards. Anyway, we had already booked a preferred room at the Movies, airfare, park tickets with the park hopper option and dme. Our TA told us that we would have to cancel the land part of the trip and rebook. She said there were a limited number of preferred rooms and they are sold out. We would have to take a standard room, and it would cost $112 to switch, since we booked as package, and we would have to pay another $70, the rack rate. So for us, the free dining really isn't free.
No worries about not getting the dining plan. Sure there are restaurants I would have liked to try, but that's okay. No worries here.