Yeah, Halo I can no longer consider it a killer app, and it hasn't been for so long.
These aren't the days of Halo 1 and /or Halo 2, where finding an awesome fps experience on a console was impossible. 
Now we have shooters out the waazu.
We got Call of Dutys annually, developed by 3 separate studos for constantly new experiences.
We have Battlefields, Killzones, Wolfensteins, etc., etc.
Halo now will only excite the most dedicated fan. As a past casual Halo player myself, I just don't care. I'm sure it'll be an ok visit for 20$ several years from now, but it creates no sense of urgency with me right now. And why should it? 
How many times have I been through the same tired fight with the Covenant trying to 'glass' our planet. And Cortana bores me. 
Pfft.
Yeah, NEXT.