Edward is a stylist, and not an editor. It's as simple as that. His editorship is non-existent.
Being lucky enough, he had his chances with i-D, Franca Sozzani, Prada, Meisel, W... But let's face the truth, his styling image is not that easily recognizable comparing to Carine Roitfeld, Marie Chaix, Ibrahim Kamara, Anna Trevelyan, Panos Yapanis, Carlyne, Lotta... So without those big budgets, brands, and iconic photographers is he really that strong image-wise? Sure, he does his job quite well but only within certain framework. Putting him as the EIC of American Vogue would be another downfall. Instead of raising new editors Condé Nast slowly lost all of them.
I would really like to see Eva Chen back to publishing business, and she could really bring a new perspective. Other names, not for American Vogue but in general, that CN should take into consideration are Melania Pan and Caroline Issa but that's very unlikely. More probable candidate would be someone like Derek Blasberg. And so we'll have not only Edward, Emanuele and Manuel, who kind of destroyed their magazines with superficiality and boredom.