As much as I want this to be true (knowing they have the money and technology for it; though a lot of key developers have left), I'm not going to get my hopes up.
Would they really have Left 4 dead 3 as it seems somewhat grammatically poor, and artistically very poor, in my view. Lol
I am not sure if Dota3 is happening. They rather have to rename Dota2 to Dota3 to keep playerbase not split. So 99% fake for Dota3. Also, where is Team Fortress 3? 100% fake.
I honestly doubt Valve is even capable of making a new Portal, L4D, or Half Life game at this point. Game development is like bodybuilding - if you're not constantly working at it, you loose it. They haven't worked on these types of games in years now, and there's been some turn over with their talent pool. Highly rated games that came out years ago are not leading indicators of future success. That said, I would love new Portal and L4D games. I couldn't care any less about HL or DOTA, but I get people love those franchises.
Sorry someone who claims to be the big cheese over at Valve has released a single image that has a bunch of highly desired and anticipated games on it... well it;s obviously fake. Valve only announce new games through the medium of obscure file naming and hidden easter eggs contained with in other games. Making an out and out statement, doesn't seem like Valve at all.
We all know that HL2, episode 1,2 and 3 were supposed to be 'HL3' so the next version (if it is ever released) would actually be 'episode 3' of 'HL2'. If I can find the Mark Laird comment and correlatory Gabe Newall comment, I'll link it - but yah, in the future, you'll know it's real if they announce it as Episode 3.
OK, so, other than clicks and comments, what would Newell stand to gain from a false facebook post? And, what would he stand to lose?
Oh, but they were - there was in truth (over ten years ago) never a plan to release HL3, but instead to work through the existing project files and break up what was left over (post-development of HL2) into 3 episodes. I'll get the links for you...