Left 4 Dead 3 is in the works?

We all know that Valve does not even count to three, but from this leaked picture from a Valve tour in their Seattle offices. There is a possibility that the team behind the successful zombie co-op shooter is in the process of churning out a new game for the said series. It's been a while since the last game, but my sentiments will be welcome to the new game of the franchise.

Since Left 4 dead 1 survivors are acquainted with the Left 4 dead 2 survivors thanks to the FREE DLC that valve has been giving out. What's next for this new game? Are they going to be cooperating with each other, or are they going to be killed off in lieu of this new game's set of survivors. Left 4 dead 2 is well alive on steam, and for a game that has been 4 years old...it stands the test of time, as it still is one of the finest co-op shooters out there. Well kept alive with mods and passionate people who make campaigns for this game. Let's just hope for the best and may Valve bring us another great addition to their legendary portfolio of games.