If you look at this stuff....go to a park or something else active
First off, Bungie may very well be working on a brand new Halo game. They said, "There are no more offshoots or side stories in the works."
That means, that the day after, they could have started making a brand new Halo game. I would love to see some new games coming from Bungie. They haven't abandoned Halo, they're simply just moving off of this BIllion-Dollar-Donut for a while. They will probably call the next game something else because H1, H2, and H3, were about the 'halos'.
Most likely, Bungie's next franchise will be much bigger. They have called H3R and the two map packs yet to come out "little new material." So...hopefully their next game will be bigger than H2.
Most likely, the vidmaster achievements, will somehow give you a bonus in H3R.
But I have one question: Will there be a demo or beta coming out for H3R? Many other games have done that, including Halo 3.