(1/2) The fanbase is torn between thinking next main game will be Alola 2, Kanto revisit or Sinnoh remakes. While all of these are viable they'e also very predictable. A return to a region from previous generation, the one that still feels very unfinished would be a lot more surprising

But thats not all of course. Lets go through other hints or reasons
>AZ Floette in the code of SM. Its still there for some reason while Cosplay Pikachu for example no longer exists in SM code. Moreover Light Of Ruin got updated animation
>Zygarde. Sina and Dexio tell you Zygarde must have some reason to be in Alola, they even suggest we will find out what it is but we never do
>Resolution cave is a replica of Terminus Cave in Kalos. We dont know why or what is it for. Guzzlord (who resembles Zygarde a lot) is in there
>Sycamore discovered the Zygarde cube and gave the mission to collect cells and cores to Sina and Dexio, we dont know the goal of that mission though
>Samuel Oak claims Sycamore helped to invent Rotom Dex which means people in Kalos probably use those now too
>Masuda in August/September 2015 was traveling through Southern rance to "study". That sounds like a good moment to search for inspirations for the rumoured Southern Kalos in the games. Just to clarify: i know they've been fully working on SM at that point but you have to realize they start working on the games way before they anounce stuff. For example Ohmori was chosen to be director of ORAS in late 2012, that a year before XY was released. Pics

https://twitter.com/Junichi_Masuda/status/637532967410098177

https://twitter.com/Junichi_Masuda/status/639176248112058368
https://twitter.com/Junichi_Masuda/status/638247970534649856
https://twitter.com/Junichi_Masuda/status/638306298711314432
https://twitter.com/Junichi_Masuda/status/638682782533840897
https://twitter.com/Junichi_Masuda/status/638760395088375809
https://twitter.com/Junichi_Masuda/status/638990205781848064