I remember back when BW was brand new and a lot of people were saying it was like a reboot of the original series, mostly due to the group dynamic. While I didn't quite get that feeling with BW, the group in XY is already giving me vibes of the AG group. From the opening it looks like we'll have a group of 4 again, and I really liked that about AG because a group of 4 just leads to some great interactions.
Serena kind of reminds me to May, with Serena not wanting to do Rhydon racing and May not wanting to challenge gyms. To me it kind of seems like Serena won't know what she'll want to do right away, similar to May before she discovered Contests. Plus they went back to using the player character as the main female of the group, and judging from the promos it looks like she'll be a beginning trainer as well.
Then you have Bonnie, the younger sibling who's not old enough to be a trainer herself but still loves pokemon, similar to Max. Though they both have opposite personalities and unlike Max, it seems like Bonnie will befriend/get a pokemon by the opening, its this role that makes the group feel well rounded for me. If you took Max out of AG then the group wouldn't work so well. It would be like a missing puzzle piece, and I think it's be the same way if Bonnie wasn't there with her brother (though it wouldn't make sense if she wasn't there since she's there in the games ^^')
Plus we don't really know if Ash will have a main rival this series (unless maybe Serena becomes his friend/rival since who says that rivals can't travel together.)
He went through a majority of AG without a rival until we got to the League where Morrison was introduced. In the games Calem/Serena is your main rival and I guess you could say that Shauna played a role similar to Bianca though not as big. Plus Ash always argues with the female he's traveling with at least once so I could see him and Serena butting heads a few times. ^^'
I know it's super early to judge but so far I think that the group for XY will have a similar feel to the AG group, with Ash as the main star, Serena as the second star (even though May wasn't an equal co-star to Ash like Dawn was I still consider her the second main star), and Clemont and Bonnie as supporting stars like Brock and Max were.