One thing I can feel safely about is that everybody in the party will have to have some sort of park ticket on the reservation. Gone are the days when AP holders could book a room with four guests to get
free dining, but only having to add one, one day park pass to make it happen. So you might want to wait on buying AP's so that if fd does come out for your dates, you won't have to purchase add'l tickets.
In the end, its anybody's guess.
To get free dining even AP holders have always had to buy at least one day park tickets for
everyone in the room.

We go every year for free dining and have since the first year free dining was ever offered. We've always had to buy at least one day tickets for everyone in the room. This past year Disney changed the rules to require at least 2 day park tickets for
everyone in the room, so the AP discount beat the free dining for us and we went the AP discount and then paid for the DDP. We were there both in Oct and again in Dec while free dining was going on. Both times we used the AP discount and then paid for the DDP.
I'd also double check this info as well. When we last had AP's we got dining without adding tickets. There is a method for booking for AP's that does not require ticket purchase.
There's a discussion of it on this website:
http://www.mousesavers.com/meals.html#diningplan
AP holders can pay rack rate or use an AP discount and then
purchase any of the DDPs, without buying a park ticket, but to get
free dining even AP holders must purchase park tickets. Again in past years all we had to buy was a one day park ticket for everyone in the room, but this past year Disney started requiring at least a two day park ticket for everyone, so free dining is no longer as good a deal as it used to be for AP holders. I have a trips booked for May and also for next Sept and decided not to go with free dining even though it was offered for my dates. I'm currently booked with the GP 25% off code for both trips, but am hoping for an AP discount to come out, so I can not only save a little, but so I can also add the DDP without having to buy anymore one day park tickets we don't need. To use any GP discount, even AP holders must buy one day park tickets in order to add the DDP and to use the
free dining offer, we have to buy at least two day park tickets for everyone in the room.
The only people who can get the DDP without having to buy park tickets for everyone in the room are AP holders who are paying rack rate or using an AP discount for the room, people staying on DVC points, and people using the military deal, but even they have to buy park tickets and can not use a room discount in order to get
free dining.