The class and/or Sylvanas spec would be called something else. Hopefully they wouldn't do a metamorphosis warlock thing again.
I am not so sure it would be an Alleria class when Sylvanas is much more popular and they seem to be building up Vereesa for something, to the point they flat out refuse to have her appear in TWW.
"Windrunner Class" makes way more sense IMO. Spellbow? Ranger? Farstrider?