I doubt we'll ever see any drastic changes to the formula. SE won't want to risk a huge overhaul after their smaller experiments like Verminion and Diadem didn't take off.
Most likely we will continue to see periodic additions of new content alongside the basics.

I don't mind it myself since I enjoy the staple elements like dungeons, beast tribes, story quests, ect. I do hope that future experiments like Deep Dungeon are successful as more content is always welcome.