There is no guarantee that there will be a free dining offering next year. The time period this year was considerably shorter that the previous two years. That said, I believe free dining has been announced in April all three times.
we were offered a bounce back free dining plan (traveled 9/29-10/9) if we booked before Oct 12th and before we checked out but it was for Sept travel. There was no explanation on that sheet talking about the changes in the dining plan or even a mention that the dining plan was changing.
We were offered bounce back free dinning too. Last year (2006) it was great few lines, few people, great food. This time it was much busier, more lines, the restraunts were packed. We even went the very same week. So I didn't take the bounce back offer. I thought I would try a different time of year. I was worried that as free dinning becomes more popular the parks would become more packed.