There was a fairly meaty video presentation on 8.2 content today, and a bunch of additional videos by content creators who have had a chance to play the PTR and talk to developers. wowhead has a ton of articles, and will have a ton more when the PTR comes up next week. It's a pretty meaty patch and I'm not going to try to summarize.
According to Taliesin, we should expect the Azshara raid to come quickly on the heels of the 8.2 patch, not after a 6-7 week delay like most Legion and BfA patches. This might mean Blizzard is taking feedback about time-gating to heart, or it could just mean that 8.2 is taking longer than they wanted.
One unanticipated change is "mount equipment". As I understand it (some of this came from the Taliesin+Evitel video, and the level information came from a recent dev tweet):
* You will get a single per-character mount equipment slot at level 20 (as long as you have one character of level 100).
* There's a mount equipment to provide water walking, one to prevent dazing, and one to grant reduced fall speed.
* They will be created by crafting professions.
* Whichever one you slot in applies to all mounts (well, almost; see the last point).
* You can change it at any time, but the old one is destroyed.
* The water striders lose intrinsic water walking.
* If you own either water strider, you will get free inflatable mount shoes in the mail, and the ability to buy more of them from a vendor at low cost.
* The sky golem does not lose intrinsic herb harvesting, but doesn't benefit from mount equipment. I imagine this also applies to the swimming mounts (sea horses, turtles, etc.) but I'm not certain.
There has been some backlash about this change due to incomplete information, but I don't think there are any nerfs relative to the current situation. If you have a water strider, you can just put on the free inflatable mount shoes and lose nothing.