You know, maybe Rare have chosen not to make Banjo-Threeie into a platformer, because the Xbox/360 audience clearly don't like platformers (going by sales for other platformer titles on the Xbox & 360 systems).
After all these years since the MS buyout, Rare really need to start making money since basically every game of there's for the last few years has been a sales flop (except DK Racing DS), and maybe they have come to the conclusion that developing a bright, colourful platformer, fighting oversized carrots with faces, is not going to sell on a system that is most popular for the halo's & pgr's & bioshock's & GoW's...