Will there be another left 4 dead

Probably not this year. Valve is known for not liking to make a third sequel to their video games. You never know though, maybe they have been working on it since the release of Left 4 Dead 2. On the other end though, Left 4 Dead 2 was released just a year after the first. Honestly, I think no though. Valve will probably add more DLC's (Downloadable Campaigns.)