It would appear that the Sonic game with double the Sonic is, in fact, coming to Nintendo 3DS, as already semi-announced by, well, Sega itself. But Shinobi? Well, that’s good news too. Thanks, Nintendo Power magazine!
https://kotaku.com/sonic-generations-may-not-be-just-a-ps3-and-xbox-360-ga-5802846
Sonic Generations for 3DS is the cover story for (what is allegedly) the next issue of Nintendo Power. That game has only officially been announced for the PlayStation 3 and Xbox 360, but 3DS and PC versions were hinted at by a recent Sega financial report.
Joining Sonic Generations (and Mega Man Legends 3) is another “classic revival,” Shinobi. Exactly what that entails—Is it a side-scroller? Is it a 3D action game a la Shinobi for the PlayStation 2?—I don’t yet know, but seemingly soon we all will. (It’s worth noting that resume scavenger “Superannuation” recently spotted a mention of Shinobi 3DS in development by Griptonite Games.)
Who’s getting really excited for E3?!
Nintendo Power Confirms Sonic Generations For Nintendo 3DS [Sonic Stadium]