If it's linear, no thanks. I haven't liked a linear Mario platformer since...geez, SMW2, if that counts. NSMBWiiU is okay, but mediocrity is not what I've come to expect from Mario platformers, and yet since Galaxy, these more linear games have been all show (Galaxy 2 is straight up the most aesthetically-pleasing game ever made as far as I'm concerned) and no go.
I love Mario overall and desperately want to love the next Mario platformer, but it needs to hearken back to 64 and Sunshine in terms of design.
Of course, if it's open world, it gets my money day one and will probably end up in the running for best game ever made.