This game is constantly balanced this won’t change with the addition of a new class. WoW desperately needs new classes, not just a new class, but new CLASSES. New classes and races are the lifeblood that keeps expansions going.
Look at the expansions that people remember fondly, they’re expansions that introduced new playable classes.
TBC gave paladins and BELVES to the Horde, Shamans and Dreanei to the Alliance.
Wrath gave us DK’s.
Mists gave us a new class and race.
Legion gave us a new class and ostensibly two new races(cosmetically, and thematically).
WoW NEEDS to introduce new classes, and can’t afford to do otherwise.