Alot of people want Johto to be in now that sinnoh is "finished" with but I think we should first add is more mmo like features. Dungeons/raids. Maybe call them hideouts/liars to make it feel more like pokemon or whatever. a team(link) of 2-4 players crawl through it fighting wild mons or trainers, at the end they fight a big boss or leader trainer and are rewarded with stuff. this could be a good and fun way to add non uber legends like Latias/Latios, the kanto birds, the regis etc. Other rewards can be Hidden ability pills, cosmatics, or maybe even some sorta item that makes your pokemon shiny? the later might be a bit to much but yea.
We dont need Johto since we have all the Johto mons and to add another region when Hoenn's battle frontier is not even finished let alone sinnohs is a bit much and unneeded. game needs to feel more like an MMO I think rather then just an expansive romhack with all the regions. team is doing a great job but this is just how I feel the next step should be. Adding Gen 6 is an awful idea no offense to anyone since the game doest need more regions or more pokemon but more features. dont make the same mistake gamefreak is doing by just adding in new pokemons. Luner and halloween events are fun new things to do and wish something like that happend year round.
First type posting on the suggestions box I dont know if "its within the realm of possibilities or not" but I hear devs here wanted to do something like dungeons/instances so just thought id shoot my idea.