Valve is working on Day of Defeat 2 instead which I've never played so I won't judge. I want HL3 as much as the next guy but I'm not passionate or petty enough to go out and protest for it. Portal 3 doesn't sound like a bad idea but Portal 2 already has a great campaign with a pretty clean close, co-op multiplayer which I have yet to try out and community test chambers which will extend the life of the game for a lot longer than the first one.
Natick
If we clearly aren't getting any announcements for HL3 then hopefully, there will be a demo of GTA V.
saltovergray
Rockstar won't be at E3, they will be holding their own conference outside of the time period of E3. But I seriously hope we do get a demo of GTA V. HL3, I don't really care about TBH. I might be a little excited if they announce Portal 3 or something fun.