It is worth reading A Knight of the Seven Kingdoms and GRRM's "history" of Westeros for various other backstories that are not explored in the tv show, and only hinted at in the books. Whether there is anything left of the Blackfyre underground after five failures -- other than the Golden Company -- is an open question. But still, the prequel stories give an idea of the depth and duration of the intrigues that are rattling around in GRRM's head.
I'm sure someone else was plotting way before Robert's Rebellion. ;)
Yes, I’ll tackle those when I done with “Dance”. Then it will be...a long wait probably. ;/