rian of GGG answered a bunch of questions people posed in a Twitch chat recently and someone on Reddit posted a screenshot of his answers. However, the screenshot is kind of confusing (most of the time the question isn't included with the answer), repeats a bit, etc. so I wrote out the general gist of what he said below.
Keep in mind this isn't necessarily stuff that will be in the next content patch, but is just some general info on some common stuff people have been asking about.
Stun is not working as intended right now
When fixed, stun will essentially make it so perma-stunning bosses or super high health uniques isn't possible (not to say that you can't make a great stun-based build, but you can't PERMA-stun them)
Current OB plan is an average of 1 new skill a week (ie: 4-5 per monthly content patch). Their biggest focus on content right now is more skills
Melee is getting some huge improvements soon
Duelist is recognized as having fundamental problems in the passive tree, will get some love
There are mods that are intentionally weaker, but NOT intended to be useless (so some may be buffed a bit, opposed to flat out removed)
They're working on Mac support
Cleave will be improved a lot
Crossbows are a possibility, though not guaranteed
AOE claws coming very soon
Unique 1h axes coming
Lots of armor/shield aesthetic items (microtransactions) in development
Act 3X (the post-Act 3 stuff, but before Act 4) mentioned (they've discussed it in interviews before)
They're internally testing out variations on floating combat text & enemy health bars
Tons of different leagues & races coming
A Diablo-like "Whirlwind" skill is coming
Phase Run will be reintroduced when it's designed as originally intended
New methods for casters to gain power charges coming
Microtrans. name changes a possibility
Current chat window is a "very very rough implementation", will be getting massive overhauls soon
Actual resistance numbers behind the capped ones (so you know how over you are) are a possibility
A support gem for "single target Cleave" coming soon
Very very unlikely loot drop system will change drastically (either pure FFA, or 'instanced'). What WILL change is timer adjustment (and what gets them)
A sweep-type attack for 2h swords coming (which is why sweep attacks don't work with them right now)