Speculation time!
By the looks of it, FRF is about the conflict between wedge-based Clans and Allied-colored Dragon broods. Ugin died, which made the Clans win and that led us to KTK. Now Sarkhan will save Ugin. I'm calling it now: DTK will be an allied-colored Set, showcasing the victory of the Dragon broods over the Clans.
I'm going to guess differently.
FRF will be about the conflict between mono-colored clans with hints of wedge stuff, leaning towards certain enemy colors that in the original timeline led to wedge based clans when they incorporated aspects of dead ally color dragons that matched their primary color.
Dragons of Tarkir future on the other hand, will have the older dragons be beaten by new generations of dragons spawned, and shift the dragons themselves to enemy color pairs, and the clans will now worship the dragons or be enslaved by them or oppressed by them, but basically the dragons being dominant, and the clans will have shifted to shards encapsulated by the enemy color dragons, but we won't actually have their original clan names, those will be wiped out, but names based on the new dragon lords, so that the wedge names are retained, although it won't be a full fledged shard set, most of the cards themselves will be mono-colored or hybrid outside of the dual-color enemy color dragons, and maybe some survivors of the original ally color dragon flights wandering around. Ugin's influence will be more cemented in a 6th human clan of sorts that is greater than the others who serve/follow/worship ugin and have a colorless focus.