Hi, Janet! The free dining offer is a fabulous way for people to enjoy Walt Disney World for a little less out of their pocket! It's really a wonderful promotion when you are able to take advantage of it.
Unfortunately, we don't know from year to year which promotions will be offered. The free dining promotion has been wildly popular, and it has been consistently offered for the past several years, but we have no way to know whether or not the same or a similar promotion will be offered at the same time next year.
I would say that if you want to travel to Walt Disney World in August of next year, go ahead and plan your vacation. If a promotion becomes available, you can always call back in and rebook your vacation trying to add whatever promotion is available at the time. If you are booking with a travel agent, many of them will do this for you automatically if you let them know that you want them to.
I wish you happy planning!