Do you mean they are going to bind the relese of their next game to relese of Steam controller and Steam OS in 2015? Don't forget they moved TI4 from August to July, which means they have plenty of time to prepare for Gamecon in Colone. I want to believe.
Hundreds of zombies getting thorn...
Valve has been releasing 1 game a year lately. So if my calculations aren't wrong, we are going to see a Leaf 4 Dead trailer this Fall.
Which makes sense actually, l4d is the best game to show what the new engine is capable of.
Not sure if relevant, but my Half-Life 2 Episode 2 just updated for 83mb, with no change logs. One might think it is a Sourse Engine update, but CS:GO or TF2 didn't recieve any. Last time a Valve game updated with no changelogs it was a teaser for Portal 2.