Info I’ve gathered so far (man these things sneak up on you!) from Retro and Stadium:
-Sonic Lost World will be the next main series Sonic title. It is WiiU/Nintendo3DS exclusive. More info here, but there’s not much, only the previously posted piece of art. The world seems to contain multiple, differently-themed zones as usual, but no word on gameplay. More details will be released before E3.
-Nintendo and SEGA have created an exclusive partnership for the Sonic the Hedgehog series. What does this likely mean? Over the years to come, major Sonic titles are planned for Nintendo consoles only. I emphasize the word planned. Nintendo will have the next three major Sonic titles to themselves, with no cross-platform sharing. However, smaller digital titles will likely still be seen on other platforms, and there is no word about whether SONY/Microsoft will get their own exclusives (my guess is no). More info here.
-Mario & Sonic at the 2014 Winter Olympics has also been announced, and of course, it will be WiiU/3DS exclusive. Whether it will be modeled after Sochi like the London game or not is unknown, but so far it looks just like the original MS Winter Olympics game. Many screenshots can be seen here.
-One Sonic game other than the last two has also been announced, though its title has not been revealed yet. It may be revealed at E3 (or any time, really).
I’ll do my best to keep you guys as updated as possible on the situation, especially in regards to Sonic Lost World.