As much as I want a true 3D mario title, the last thing I want it to be is Galaxy 3.
Super Mario Galaxy is one of the greatest and most well designed games of the 7th generation. The amount of creativity shown in the game is almost mind blowing. I've beaten the game atleast 5+ times. But, I view Galaxy as it's own standalone masterpiece, similar to games like Metroid Prime, I always felt that the game didn't really need a sequel. But it got one.
Galaxy 2 wasn't a game I owned until 2013 when it dropped to $30. It was a major disappointment, in fact I'd go as far to say that it was my biggest disappointment of Gen 7 aside from Twilight Princess and Super Smash Bros Brawl. It just felt, for lack of a better word, shittier.
The condensed overworld was unexciting, the Yoshi mechanic I found to be dull, it was too linear for a "true 3D mario", the levels we're too easy, and the power ups we're just meh. It's not at bad game by any means, it's just "shittier" than the original Galaxy.
If Galaxy 2 was like this, I can only imagine what a Galaxy 3 would be like. I would much rather have a game in the same vain as Super Mario 64 or the original Galaxy. Unfortunetly, Galaxy 3 has sort of kind of already been confirmed by the creator who said that they weren't abandoning the Galaxy formula. I can only hope that they make use of the Wii U's capabilities and make the scale of the levels and the overworld huge. If it isn't I'll just keep playing 3D World to be honest.