Update 18 will increase the level cap to 105, and so begins the armor grind all over again. The top tier gear will come from instances, no surprise there; one set for each class from the new Pelennor instances and another set from the new featured instance of the week. A vague line in the patch notes of beta round one gives us a little extra information about featured instances, but we anticipate a developer diary on the subject with further details about how rewards work.
For characters level 100 and higher, the Featured Instance can be accessed through the Instance Finder Specific Tab and will award extra rewards once daily for completing the listed instance. The Featured Instance will change weekly. Source
The screenshots below are from Beta round 2 except for the Rune-keeper tooltips which were updated in round 3. The loot tables haven’t been set up for the instances yet, so it is unclear the exact mechanism for obtaining these sets (i.e., random drop, choosing a piece from a lootbox).
Featured instance sets
In addition to the blue (incomparable) jewellery set that comes in the Agility, Might and Will varieties, there are sets of rare (purple) jewellery possibly from tier 1 instances or as more common random rewards.