Honestly, there is no telling where this game is going to go.
It sounds like it is going to be a
Super Sonic Galaxy game but that was only because there will be different worlds and strange alien creatures along with Eggman taking his plan into space.
This game will probably be like Super Mario Galaxy, probably not.
Super Mario Galaxy had different galaxies as levels with a range from many to few few planets while Sega says this game will have different worlds, shares similarities but no one will be able to make a completely supported "OMG TOTAL SMG RIPOFF!" statement until the game is released since we saw no gameplay yet.
Also, did anyone notice this and Sonic 4 will be released both later in the year? Sonic 4 in the Fall and this at the Holidays, presumably one or so months later at Christmas time.