Wood Elves is a major faction in the warhammer world and definitively they will get min. 2 additional legendary lords in the future updates.
One of such legendary lords should be a powerful spellcaster (Am I right or wrong?
Do we need a powerful spellcaster in the WE faction? ).
If Ariel will be just a game mechanic (for example will count as special hero, which you will include in yours LLs army or just be a magical spell), who will take her place? maybe Naieth the Prophetess?