In the latest Midnight Developer Q&A, Blizzard confirmed 
Valorstones will be removed in the Midnight expansion.
Valorstones are being removed in Midnight
byu/COCAINAPEARLZ inwow
What Does That Mean?
This means Valorstones will no longer be used for gear upgrading. In Midnight, you’ll only use the relevant crests to upgrade your gear.
How Does the Community Perceive This Change?
Overall, the community is happy with the change, as Valorstones created more problems than solutions. You either had too many or none and there was really no middle ground.
Comment
byu/COCAINAPEARLZ from discussion
inwow
Although Blizzard tried fixing some of the issues by making Valorstones tradeable with the Turbo Boost events, they’ve now decided to completely remove the currency.
