Reports from Geek say that Ego, which was a living planet will most likely to be appearing in the Guardians of the Galaxy 2 and this will be the first time that Ego will be seen in any of the Marvell Cinematic Universe even though the character has some of the connection with the Thor in the comics.
Ego first appeared in the comics in 1996 which resides in the black Galaxy and the story began as any planet does, coalescing from dust and all the cosmic gasses for over million of years. Ego comes into consciousness when the stranger come across the planet and gave him the consciousness. In the comics, Ego cross paths with Fantastic four, Silver Surfer, Professor X, Iron Man and Thanos . This time, Guardians of the Galaxy 2 Rocket Raccoon crossed paths with Ego when he tries to destroy the earth.
While there is no telling right now how filmmakers will introduce Ego and a living planet into the Guardians Universe but it is clear that he has a lot of history to mine for story purpose and he could also be a minor foe for the intergalactic space heroes.
You may be not simply thinking hard enough if you consider there is no way a sentient planet could work in Guardians of the Galaxy 2 movie. Ego can rather fit there better than any Thor or Iron Man movie after all the director simply brought tough little rocking racoon and a giant, sort-of-talking tree man to a big screen. The filmmakers can easily think of new way to fit Ego in the story as he is the right up their ally.