To be honest, I just can't see the Freedom Fighters in an official game (not 100% sure if I count Sonic Spinball or not.) As much as I love the characters, I've always accepted them as part of their own continuity within the cartoon (and Archie comics, who adapted them into the video game adaptation story lines.) It honestly doesn't bother me, I just see it as a separate world entirely and an alternate timeline/universe. I'd be very surprised if it actually happened. Any news like that I'd treat as a hoax unless there's some good, legitimate sources to back it up or until I actually see it for sale, and not on ebay either since I know people make and sell fan made games on occasion.
Doesn't stop people from getting creative with mods and fan made games though, and those look like fun.
Fear of another lawsuit is a possibility as well that Sega might want to avoid.
I get that Sega of Japan does have a tendency to be strict with how Sonic is treated in it's games, and while seeing more of the American influences come out would be nice, it's doubtful. (But hey, at least we got the chili dogs right?)
Honestly though, what kind of game play would the Freedom Fighters have? I could see some potential for Bunnie given she's got the robotic arm and legs. Rotor could be given a cool robot walker like Tails had in Sonic Adventure 2. Sally I'm not sure about, having her just run around fast like Sonic seems well...inaccurate for the character. It's cool in a fan game though. It's possible she could have some kind of recon mission where she has to collect items to further the story. Sonic Adventure did offer a variety of different game plays for the characters, so a format similar to that might work. Her game play could be similar to the custom character in Sonic Forces though, and give her some grappling hooks and other accessories she could use.