I really don't see what else you can do with the series after Sunset's story arch pretty much ended in Forgotten Friendship. The closest thing you can do i guess is the Mane 6 and Sunset going to collage. With them working towards their lifelong adult goals like Rarity opening a successful fashion brand, or Rainbow Dash being a Nascar driver, Or Twilight being a CEO of a multinational corporation that sells cosmetics, chemicals, and other pharmaceuticals.......
But honestly, lets dig a hole in the garden, bury it, and forget about EQG.