Well Void Elves are still Blood Elves anyway so
Ion said BfA will be the same level at Alt-friendliness as Legion.
So, there will be something completely alt-unfriendly that will replace the Legiondaries.
The fact there is a catchup mechanic for the Azerite is enough for this expac to be alt-unfriendly. It was shit in Legion (until the moment they finally decided to give everyone the same Knowledge, which will still be an end-of-expansion mechanic, likely), and they didn't learn anything by not setting this Heart of Azeroth as unique for all specs.