Arthas should be in the game by now . And no i don't want them to put him as a legendary if they are going to rotate him out to wild two years later . Iconic characters like him , Varian , Rag and Sylv belong in the classic set, period . Either put him in the classic set or finally create the death knight class . All existing classes in WoW should be in the game . After all it's called HS:Heroes of warcraft . It feels like with every expansion we get more and more random stuff than familiar characters
That is distinctly not what the classic set is for.
Hearthstone has quickly evolved into it's own and unique environment and has created some interesting characters and really done a great job at expanding *around* the Warcraft lore in directions we don't see in WoW (Which focuses mostly on large lore events that move the continuum of the story forwards), and I love it for that.
Whether they are saving Arthas for inclusion in a "Death Knight" class (Which I personally hope they don't add, tbh) or saving him for another expansion theme, we don't yet know, but I highly doubt we'll see him or other major lore characters slotted in to the Classic set, without major revamping of what the Classic set is fundamentally.