I would really like a dynamic soundtrack that changes depending on the time of day, like Diamond, Pearl, and Platinum. I don't know why Nintendo removed the feature for all the future games, but it added so much immersion to the games. 

For example, the subtle difference at the Pokemon League depending on whether it is day or night

https://www.youtube.com/watch?v=IPBO3l4K7HU

https://www.youtube.com/watch?v=2nlOm6-zhgs

Or the difference on route 209

https://www.youtube.com/watch?v=qAH6hNFkHTw

https://www.youtube.com/watch?v=yeUV_Vy6Dto

They are subtle differences, but they added so much to the atmosphere of the game, especially since each area had its own unique music depending on the time of day. 

I want it to keep the everything XY introduced. AKA the competitive mechanics.

That would be awesome! XY features + stuff like that = Cannot wait for this shit!

Definitely, and for the love of god, please don't remove the trumpets!

Mine would be to improve the secret base feature. That was awesome!

I never really used this feature but in DPPt I was a huge fan of the underground section so I would love if they added to the secret bases... especially now with online =D

And secret base streetpass function!

The only person Ive ever Streetpassed is my sis, well outside of the KI:U tourney I went to

I hope they expand the Regional Pokedex and add some Pokemon from Gen V. Most likely Pokemon that aren't catchable in X/Y will be in the R/S remakes since GameFreak usually make it possible to obtain all Pokemon in a single generation.

Also PLEASE use the Emerald story arch; It's so much better!

Ah, so I'm not the only one liked the music alterations based on time of day! ^_^