All good questions, but I'm kind of stunned people expect an answer to all of this today.
I remember back when the Argus patch was announced by Ion at Blizzcon and there was a ton of "what ifs" and "are we doing xs" questions and people were freaking out... and literally all we were given was one single image and his "we're going to Argus." And that's all we got, and yet the patch basically sustained us through, what, six months? Longer?
If there's a Dark Ranger hero spec there needs to be a 'good' version based on Alleria.
Started in closed beta, probably before your class was even in the game.
Yes, game should be like Diablo 4 on this. Doesn't matter what you play, you progress your account. Of course there should be always way to repeat any content you want - not only on alts, on your main too.
I would go even further. If all transmog is account wide, what's even point of repeating same quests? Just make toys, similar to exploration ones, that finish all zones on continent for you if you are max level. No more ton of random quests everywhere which you have 0 interest in cause you already done them.
Of course to avoid being jack-of-all-trades in professions, it still would have to be limited some way. But Blizzard already intenveted solution for this - knowledge points. Just make them universal currency with limited ways to obtain them on single character.
Second way could be also picking 2 active professions on single character, just like today, still with account wide recipes of course. Switching profession would cost let's say 5-10k gold, so it isn't punishing if you really want to switch it, but makes trying to get rich on using all professions impossible.
Maybe in the Last Titan expansion, we'll be fighting the Titans instead of the Void, with Aman'thul as the final boss, for example. Didn't the announcement mention the suspicious side of the Titans?
Anduin doesn't want to rule, so Turalyon is busy keeping Stormwind together.
Alleria was always action-oriented and didn't want to remain idle during a major crisis. This defines her character, so it makes sense that she leads the investigation of the World Soul while Turalyon, who was always the more "diplomatic" of the two, stays in Stormwind and rules.
As for Arator, they remembered him in the Corrupted Visions. Let's see if the vision will come to pass and Alleria will actually sacrifice his son to the Void.
Both Parents elected to go fight in a War. They weren't forced to. And they knew they might never come back anyway, in the form of dying in that war. Did they even win that war? Did it matter because the planet was going to explode anyway? Awful Parenting on every level.
Lessons learned from previous expansion reveals. It is called "experience".
Do we get a new class? No. Do we get a new races? Nope. Do we get new profession? Nope. Do we get something new for PvP? Nope. Do we get new core gamemodes? Kinda nope, because Delves looks exactly like glorified MoP scenarios.
So what exactly new we get? New art. Which looks amazing, but it is not worth to be called a content.
After the third expac (presumably the conclusion for WoW as we know it), which race will come out as most heroic?
Started in closed beta, probably before your class was even in the game.
Anyone who's ever watched Babylon 5 knows what happens, when we meet a more advanced race everyone thinks is good, and we start warring with a more advanced race everyone thinks is bad... and it turns out they're both pretty much the same, just two sides of the same coin.
I genuinely think this is where we'll be at the end of The Last Titan.