IF Sonic Prime fits into the game canon, I doubt we're going to get some reveal about where it fits on the timeline, if it's between games we've already had. I just don't see Sega caring enough about that. I don't think they care if this series took place in between Lost World and Forces for example, and it wouldn't make for a great reveal, anyway. It's just too fiddly. I just don't think the idea adds anything to ANY of these stories, not to the games' stories and not to Prime's own story.
I COULD see Sega using the ending of the show to be a reboot of the timeline, though. In a Flashpoint sort of way. I don't think anyone wants that, but I could see Sega doing that. Deciding to just streamline everything in a new timeline, since they think it's gotten too complicated. Just throw out the past and build it up again "right" this time. It wouldn't work, and it'd be a bad idea. But, I could see Sega doing it.
Alternately, it COULD all be a origin story taking place before the first game. Like, the original Sonic world is created due to whatever happens at the end of this season. That would be...something.
A far more interesting thing they could do is use these characters in a upcoming game. Sonic Prime all being a lead up to a new Sonic game WOULD be good advertising. And something FAR more likely that Sega would do. And if they wanted to throw in a few more characters from OTHER Sonic worlds, like maybe the Freedom Fighters...well, then all the better. A Sonic multiversal crossover game. A spiritual successor to Generations, maybe? That'd be something I'd be more interested in. So, Ian would basically be teasing that this show takes place BEFORE the new game. And it'd also make sense that he couldn't SAY anything about it, since it'd be spoiling a upcoming reveal.
I've said something about this before, here:
Your one stop shop for Transformers News, Games and Comics!
www.allspark.com