I'll be okay with it, but only because Blizz has not really given me a reason to like her all that much. She is a cool character (I like the Forsaken lore so I think most of their lore characters are awesome), but I don't see any reason why she should be become a "main" character like Thrall and Sylvanas. Do people really dislike Sylvanas so much that they want a minor character to replace her as the leader? (For this thread's purposes, this will be rhetorical)
If she ends up dying in the heroics I am fine with this. A little disappointed that they built up a character like her just to make her a minor boss, yes, but I don't really see the point of trying to force her down people's throats as anything but a cool character that you met in your undead starting zone area.