It is rumored that Valve has been working in a survival mode over the last couple of updates with new commands and code words cropping up in the game files.
These files could be an indication of an upcoming survival mode similar to PUBG. If these rumors are correct then the new update will also include new combat mechanics like fist combat and weapons such as crossbows.
It should be noted that nothing is concrete information and at the time of writing and Valve have not given any sort of statement. Gamelust will keep you up to date on the latest.