#1 - June 15, 2016, 9:58 a.m.
Blizzard Post
In the latest beta build, both Arcway and Court of Stars are only available as Mythic dungeons, unlocked at an appropriate point midway through the main Suramar questline. In (hopefully) the next build, you'll see a few extra items spicing up the loot tables of those dungeons as an extra attraction once they're unlocked. Their Normal and Heroic versions were already far less likely to be seen, due to queue mechanics, and this change is aimed at clarifying the role of these dungeons as endgame unlocked content.

It's crucial to remember that while the label "Mythic" may conjure up visions of hardcore raiding and may seem intimidating for those who haven't yet tried them, the main difference between Heroic and Mythic dungeons lies in the expected item level (810 vs. 830ish) and the fact that there is no random matchmaking available for the latter. An organized group of 5 players with experience and gear from Heroic dungeons should find success when venturing into Mythic. Higher levels of Mythic, accessed via Keystones, are where the major challenges lie.