Knowing the Valve, I'm sure HL3 will be announced, but in a weird way, as is always been case in Valve's.
As for the content of HL3, all theories are possible, because something big surely Valve plans to invest in the game.
Hello everybody from Valve Time, my name is Ivan, I live in Belgrade, capital city of Serbia.
I'm in law and business high school.
I am a big fan of Valves games, especially Half-Life series.
I love beer, gourmet burgers and football.
That's all :)