I think that this would work better in the fifth generation thread, but that's just me.
Anyway, as cool as the new male trainer is, I can't really see him traveling with Ash. His designs has a few similarities to Ash's, mainly the hair coming from the side of his head, the hat and the jacket. Plus, they've never been that interested in promoting the male trainer of a new generation, so I don't really see why they'd start now. Granted, I could be totally wrong, but I don't see him showing up other than in five-second cameos in the movies. I wouldn't be surprised if Ash had some of his clothes for his new fifth generation outfit.
I could totally see the girl replacing Dawn though, if they do keep the whole change the female traveling companion every generation task that they started with May. Her design gives me the idea that she'll be kind of a toraboy, or maybe more assertive/confident than both May and Dawn. I'm also pretty sure that they'll keep Contests, which would make her the new Coordinator. I can't really see her dressing up for Contests, so maybe she either refuses to do so or that part of the Contests is eliminated and something new about them is introduced.
I'm not really sure that the ages in the game affects the series that much. Outside of when a kid is able to get his/her own Pokemon, they've never made a big deal about it in the show. Neither the male or female trainer actually look that much older than the other protagonists to me. They just look slightly taller and no older than fourteen. It wouldn't be too hard to just make her ten in the series, especially if the ages in the game haven't affected the series beforehand.
If they keep the girl as whatever her age is, then maybe they could explain why she didn't get a Pokemon at ten. The new region could have a different age limit for some reason. Or maybe they could give her a backstory with some sad/traumatic event happening at ten that prevented her from getting a Pokemon or stopped her from her goal. But after some positive experience with helping a Pokemon or a Pokemon helping her, most likely one of the starters, then she decides to be a Coordinator. That honestly sounRAB more like something from Pokemon Adventures, meaning that I doubt it actually happens like that, but it still sounRAB really cool.