>>289200840
Next update hits beta next week apparently, so 2-3 weeks. He said the same thing months ago though so who knows for sure. 

Map independent gamemodes will be extremely limiting if they don't allow custom assets to be included. Zombies is probably going to remain a mess, no surprise if it gets abandoned. WW2 update after this one, new maps and weapons with the same Pavlov gameplay is what I expect, not getting my hopes up. Lua server side scripting later in the year could be neat for managing map changes the community servers. 

Dave hasn't shown or mentioned anything concrete beyond these things, at best we have a couple of mockups like >>289201551 and weapon/map screenshots for the WW2 update.