Thinking on it, one thing I hope they do for the Legendaries of the region is draw inspiration from a wider array of mythology for their inspiration - go a little further abroad culturally, rather than sticking to more well-known ones. I'd also hope for more than six Legendaries this time around...yes, the larger the number of Legendaries in a generation, the less special they feel, but as someone who loves seeing the mythological inspiration in their designs I hope they have at least nine or ten Legendaries this time around. Six in Gen VI just wasn't enough, especially when you consider half of them weren't available in the games. Legendaries form a huge part of a region's culture and backstory, so I'd like a few more as a way of painting a more interesting picture of the region.
...don't ask me what mythology I want them to use, though. Sure, I'd like the biblical references because I think it'd be amusing, and the Omega Pokemon for that symmetry as I stated in an earlier post, but for the region's back story itself...I dunno. Maybe something Aztec?
Also, I would LOVE some more Pokemon based on Nazca lines. Sigilyph is one of my favourite Gen V Pokemon.
...and no more monkeys. I'm fed up with monkeys. Just thought I'd toss that out there.