Things I found interesting from today's dev Q+A:
* They do not have an exact date decided for the opening of Tomb, but they estimate "mid to late June".
* If you have all of the legendaries for your loot spec, in 7.2.5 you can get legendaries from random other specs. (I guess on live you can't get more legendaries at all in that situation.) If you want to target a second spec you'll have to set your loot specialization to that spec.
* When they abruptly reduce or eliminate a requirement for something, like not requiring invasions for flying, it's not always a major unexpected course correction; they intentionally err on the side of setting requirements too strictly at first because it's easier to relax requirements than increase them.
* Ion was pretty apologetic about the gap between expectations and perception for "the biggest content patch ever." Objectively they put a large amount of work into it, but the visibility of that work is finely sliced between different class and artifact upgrade quests, and also across time (not just the legionfall campaign, but also brawls, which a lot of players probably don't care about in the first place).
* There is a recent, systemic problem with lag in world zones. This is supposedly caused by players using addons which manage to convince the system to put lots of players into a single shard, overloading the servers (probably all servers in that data center, because of the O(n^2) scaling of network traffic resulting from n players in one area). They are trying to figure out the best fix.
* I think this was the first time they've officially said there will be another raid after Tomb. (They've said we're going to Argus after 7.2, and it would have been really weird if that didn't involve a raid, but they wouldn't confirm that there would be one until now.)