Re: X-Men: Part 6 should be set...
My ideas for a sequel to FC included adding two new members to the X-men, either Tessa, Petra or Sway and Thunderbird to round out the team. I'd set up Moira to start leaning to towards genetic research in the CIA.
The Brotherhood would be very active freeing mutants from secret camps worldwide. Emma would leave the team after she felt she'd repaid her debt to Magneto for freeing her.
My plot for my sequel to FC involved both Mags and Prof converging on peculiar facility, which sounds similar to the mission statement of Xavier's Institute. Their they both find that things aren't what they seem and the young mutants at the private facility may be in danger from their headmaster, Dr. Nathaniel Essex, who has "sinister" plans in mind for his wards.
Subsequently, the status quo would change in this movie having:
-Riptide switches sides again having been a plant by Essex, originally to spy on Shaw, then acquire info from Eric
-most of the Brotherhood would die (Angel, Azazel); Riptide is killed as well
-Scott joins the X-men
The final part of the FC trilogy would be Professor X recruiting Jean and Storm to help Scott return to the Island of Krakoa to rescue the rest of the X-men.
"My sheep hear my voice, and I know them, and they follow me:" John 10:27 (New King James Version)