1. Yes, in the $50-100 range.
2. One will, but not both. I get the feeling Lost Odyssey will be dated, but Mass Effect will have the nebulous Q4 tag attached.
3. No. A lot of people are assuming this will happen, but I don't see it right now.
4. Yes. MGS4 has had too many persistant rumors about its inevitable port to X360. Where there's that much smoke, there's usually fire.
5. Banjo will be mentioned, but not shown, Halo Wars will only show the same trailer we've already seen, but Fable 2 will be shown.
6. Outside of these, probably not. Although I think we're going to see some sort of upgrade in LIVE functionality -- an increased library of movies/tv shows for HD download, more media-center support, some amazing arcade changes, etc. Something along those lines.
