Disney hasn't given any indication that the perk may disappear....but then I wouldn't expect otherwise.
With ever-increasing prices, the value of the discounts does diminish a bit each year. A $100 discount on a $500 AP is a lower percent than a $100 discount on a $400 pass.
In about 15 years that AP discount will probably be 10% of the pass price. The discount will be equivalent to getting a free counter service meal.
I'm not a DVC member -- Yet!! I plan to be one by the end of next month! Hoping that because Sept. ends DVC fiscal year they will offer some great deals that will be out in the next few days .... So, I'm just trying to figure out as much info as possible!