Well, since this a catch all thread...
-Longevity, both game and postgame.
-The new Region being a series of scattered islands that we explore
>Exploration as a new/pushed for element?
>Multicultural Region! Make it a tourist trap and instill the past regions into attractions (Unova-Town, anyone?). This idea was inspired by the South Kalos-ese town (blanking on name), and I think it'll be a nice compromise if they can't compress locations.
-Kalos return pls?
-That said, South Pacific for new Region pls.
-A connection to not only Kalos, but past Regions of old.
-POKE TRANSLATOR PLEASE.
-More attractions and character to Routes
-Camping? Please? I would love this.
-Transportation for backtracking, or just cruising in general
-Full on customization. Not such a advocate for this (duetomyedgyreasons), but since GF is aiming for Pokemon to be as welcoming and international as possible, why not add more facial and body extensions as well as skin tone?
-Using the Motel as a Secret Base-ese feature? A home away from home!
-A tweak for the Meta-Game. I'm not Competitive Battler, but let's make the endless game fair and lively!
Overall, vague and lofty wants, but that's what hoping is for, eh?