I've always been a bungie fan but never a halo fan.
It isn't surprising that they find them in the position though. I would say there were lots of Bungie fans before they hopped over to the 360, but not many Bungie fans followed them over and all the people they grabbed afterwards know them only for halo.
It'll be interesting to see the Halo fans reaction to their new title, especially if its not a shooter, which I'm hoping is the case.