World of Warcraft will be getting some class set changes when Eternity's End goes live. There's an extensive new update outlining all of the changes headed to the PTR to see how well they work as intended.
One of the primary changes and goals is to have set pieces dropping from a separate loot table on every boss that drops those pieces so that there are more set pieces available via drop over time. This content update has a lot of focus on gear and set pieces so they are trying to really change and want to make these changes to class sets a highlight when the update finally drops. This aspect in testing will be to make sure that these changes to loot tables on bosses are not going to result in really uneven distribution and drops.
The Creation Catalyst gear system is planned for about 8 weeks after Eternity's End is released and will let you craft set gear that you haven't gotten from raid bosses to give you an alternative way to complete sets. They've already seen issues in the past where getting complete sets was either very slow or too fast and it threw off the pace and experience of the content. There will be cooldowns and ways of making sure the Catalyst serves as a way to catch up and not the primary way to gear up.
Other changes include having the bosses drop set pieces as tokens. Intended to be a way to help various players of all classes have a more equitable chance at getting the gear that they need. This is another aspect that they are looking forward to testing and seeing if they are successful and the right fit.
In a follow-up, they noted that tokens for this tier different classes can take advantage of particular tokens, which share a thematic link. Mystic tokens can be used by Druids, Hunters, and Mages, while the Zenith token can be used by Monks, Rogues, and Warriors. A Mythic boss will drop two tier tokens for a Mythic raid but a skilling raid might see one or three tokens drop.
You can read the full post about set changes coming to the PTR and the accompanying Q&A for more info.