I think or HOPE that Valve is just gonna have episode 3 essentially be Half-Life 3.  I think it has the potential to be a full game on its own.  If it was intended to just be another episode I don't think it would have taken this long....

Yeah, I don't get why people are waiting for a third episode for it.  I mean, I know Valve toke their time to release Half-Life 2 but episodes shouldn't even take this much time to come out.  And I'll be really surprised if that's what they announce instead of just Half-Life 3.

I feel it depends on whether its a conclusion to the half-life story as a whole, or just the half life 2 story 
 
if its the former than it will be half-life 3, if the latter it will be episode 3.

I'm not sure about that, as Valve's Gabe Newell stated that Half-Life 2 Episode 1-3 are Half-Life 3.