Slightly intriguing that the controversial companions of this summer's Movie both have gen 4 Pokémon.
Yeah there's quite a few hints.
The partner Pokemon in the upcoming movie
Gen 4 having very little representation in the Alola dex
The Munchlax giveaway when the games first came out, similar to X and Y's Torchic
Silvally's RKS System
The references to Giratina, Palkia, and Bronzong in the Dimensional Research Lab
The Sinnoh starters getting some attention on recent promotional images/videos
... and I'm sure there's more. Sinnoh is my favorite region so it's what I'm hoping for the most, but if I was a betting man I'd put money on a SM third game/sequel for the next game. Hopefully they'll come before gen 8 though. I need to listen to that chill D/P/Pt soundtrack in remixed glory.