This is pure speculation but just based on what I have been hearing from Disney reservation agents and Disney sales reps, is that IF it were to be extended (and I don't think they know the answer to that yet), more than likely there will be a minimum ticket purchase required to eliminate the number of people who are booking with just 1 day tickets. Like for instance, it may be a required minimum of 3 day park hop tickets etc.
I understand the frustration of AP holders and DVC owners of not being able to get the dining plan. I'm a former passholder, more than likely will be one again this year, and a TA. TAs can't book the dining plan either with their discount. I've complained that they shouldn't expect us to sell it if they won't let us use it. I would love to see them put together a discounted package for AP holders as well. I don't think that is likely though.