Not sure if something is planned but I'd say yes. Disney likes to have some sort of celebration each year to make it more attractive to potential travelers.
Whether its "100 Years of Magic", "Disneylands 50th", or even a "10 years of Animal Kingdom", you can bet on something new.
Frankly, I'm not sure either of those (particularly DAK) is all that exciting to the populace at large. Disney must realize that people are not gonna whoop themselves up to hysteria in order to celebrate Epcot's 25th. I'm sure they'll do a little something but they would be better advertising whatever new attraction comes down the pike.