While the whole 'farm boy wanders off into the world and becomes the hero' trope is considered monstrously overused...(realy? Overused? It happened in film three times. 3. Period: Black cauldron, starwars, princess bride). Frankly 'arrogant noble gets comeuppance' has been used more (game of thrones...a lot, princess bride).
Hero's journey keeps being touted as over used but the older version (protoindoeuropean) is Au-at-ar (avatar): to go-to fit together- to make whole. Its about a journey of healing and self discovery. It isnt about heroes or villains. Its about the person.
that next great epic might just as well be martian war machines in the american revolution or spanish explorers taking a facehugger egg from a south american pyramid to medieval spain turning it into Aliens: Dark Age. Inquisition, knights, Aliens. Hell yes.
What makes game of thrones interesting is the interaction of strong characters. Diverse characters. Everyone is a bastard eventually or someone kills them.
My short fiction, 'Su-lus' is set in Mystara. Focusing on about 800 words a chapter it pretty much wrote itself. Mostly it was one character: who is in the D&D setting a nosferatu. His progress toward that destiny provided a pretty good read. It was certainly fun to write. Doing that for a dozen different characters is what will make Mystara or Forgotten Realms or Greyhawk great as a series on tv or to a lesser extent...on film.
That next game of thrones?
A. Any D&D setting
B. Alternate History
C. Science Fiction
Belgariad is not the same intensity as Game of Thrones. Not by a long shot...
Epic challenge: Game of Thrones the hell out of 'Pawn of Prophecy'.
Not a chance?
Then the bible is not for children either. A fisherman of dubious birth starts a vile religious cult that lasts two thousand years.