The release date has been set to Q4 of 2018. This provides enough time to finish the last few mechanics, do QA and reiterate to fix bugs and anything else that's required.
The main thing being worked on at the moment is network synchronisation of.... everything (and optimising the implementation). Here's a quick overview:
Multiplayer games can be a lot more complex due to the networking side. The main issue is synchronising things like player movement, speed, turning, shooting etc on all connected clients.
Commands are called from the client and run on the server; and client remote procedure calls are called on the server and run on clients.
When another player in the game moves, runs, shoots, or does almost anything - it gets sent to the server as a command, which then sends out a call to your client, allowing you to see their synchronised actions.
Optimising these calls is a priority as it directly contributes to network traffic, increasing server costs and potentially slowing down the game.
One way to achieve this is through the use of hooks. Basically, calls are only made when a variable changes. Therefore, if a variable (player health) does not change, a remote procedure call is never made.