Like someone else said, there's an article about HL3 not appearing in any shape or form in 2014, which pretty much tells me that HL3 will be appearing in some shape or form in 2014.
I enjoyed HL and HL2. My main comp still has HL2 and its episodes installed, just in case one day I do decide to finish Ep 2. In all likelihood, I never will, but I might.
I'm not excited about HL3. The landscape has changed so much. If and when it comes, it being available for consoles, doesn't effect my interest in the PC version either positively or negatively. I can't yet imagine what truly new elements could be added to the series to make it a stand-out.
It could end up being open-world, with "shadow of the colossus" boss fights, tomb raider dungeon like levels with puzzles, scripted events like "God of War", press this button now omgz or u die, one button press instant kills while sneaking, oh yeah, splinter cell type stealth missions, and AI controlled companions that either aid you in battle, or must be escorted to safety... Hmmm...
I hope HL3 brings brand new tech that wows the eye, living, breathing environments, and a new level of quality to enemy artificial intelligence. Let's hope if I can see an enemy, it can see me too and reacts accordingly lol.
The hopes and expectations for a HL3 might be too high, and leave the developers second-guessing their decisions throughout the entire development.