I just feel like ODST really took a huge crap all over the brand. everyone played Halo 3, less than everyone played ODST, and no one at work seems excited about Reach - the reaction is more "oh, God, more Halo."
everything about Reach looks like furious backpedalling to make it a "return to our roots" which is usually the line you start trotting out when a band/artist/brand is so creatively stagnated that nobody knows what to do with it anymore but by God, you need to keep pumping out content.
I don't doubt it'll still sell very well (of course) but I think it will come in significantly under 3 and even a bit under ODST