I mean... There's no real way to know unless you're a Tripwire insider. It's not as if they teased specific maps or something.
We simply know that for the last few years, every update contains :
-1 new map (lately, those are always made by fans and don't really follow the event's theme)
-1 or 2 new HRG weapons
- 1 or 2 DLC weapons
- 1 or 2 new weeklies
- Some hotfixes and balance changes
From there, we can't really guess what's gonna come. Sure, the topics dedicated to coming up with weeklies and weapons might be a guide (as some ideas got turned into the real thing), but that's pretty much it. If there's one thing I can praise Tripwire for, is surprising me with their weapon choices. Not always in the best way however.
EDIT for
@Nac : yeah... a gun that can auto-lock on zeds doesn't sound like the best idea. But then again Titanfall proved that it was possible, even against human opponents. Then again the Smart Pistol takes a little while to lock targets and it has a reduced range... Maybe that could be the way to go? But then I fear the exact opposite : people waiting for their gun to lock-on, costing precious seconds, for results that could have been achieved easily at such a close range anyway.
But it's not a harsh no. I mean... The Railgun locks on directly on WEAK points, for the tradeoff of doing less damage. The Seeker Six, despite its lock-on ability, is often frown upon as being far less effective than the good ol' RPG-7. So the matter would be, as usual : balancing.