If Marvel and Fox come to a deal or came to a deal over the X-MEN and in 2017 those plans bear fruit.
After Hellfire, and Legion, I would love to see Agents of SHIELD use the High Evolutionary to bring back Quicksilver to life, I think he could work because it is an Inhuman who teaches him how to unlock the genetic code.
He could be the one that gives Quicksilver Isotope-E which makes him faster like in the comics, but his speed is going to be increased closer to 616 Quicksilver levels, along with 616 Quicksilver's exact abilities like Time duplicates, and what not.
Have Agents of SHIELD discover him because he can't control his powers he is going in and out of speed can't slow down when he wants to, he's creating temporal clones by walking, yadda yadda.
After an Avengers X-Men Crossover movie on how to handle the mutant Legion a very dangerous unstable mutant, Phil Coulson puts a new team of Avengers together with a roster of: Quake, Mockingbird, Quicksilver, and Scarlet Witch( maybe)Wolverine, Beast, Spider-Man, Hawkeye and Captain Britian called the Secret Avengers Season 5 of Agents of SHIELD
Agents of SHIELD: Secret Avengers to deal with high powered mutants, Inhumans and enhanced or a MCU Movie
Have the High Evolutionary be a Agents of SHIELD villian for a while like 1 or 2 seasons.
The X-Gene( A Modified Inhuman Gene strand that is gives the person with said modified gene superhuman ablities through puberty, without terrigensis, it was made by a faction of the kree trying to make a more efficient super soldier and forsaw a lack of terrigenesis crystals using Celestial technology, the Inhumans we know the regular Inhumans were made by a faction of the Kree that believe Inhumans should be prepped because the results are unpredictable)