I agree with LastNight that it would ring insincere on EE's part if he does jump ship, but to be honest, we've seen this before. Tina Brown remarked in her memoir that Grace Mirabella knew her job was in jeopardy the moment Anna got the House & Garden job. With Anna's brilliant record at the time, why would she move from a succesful UK Vogue to H&G? She may have been promised the US Vogue position while she was at UK Vogue and as such knew her stint would be a preview. H&G was just a temporary bide and to refresh herself in the American realm. After all, she stayed there only for 10 months before replacing Mirabella.
Anyway, to cut a long story short, I don't think we should rule out EE. His changes so far has been superficial. What I'm seeing is a stylized American direction superimposed onto a British edition. The proof that he can lure in not only pop stars (US Vogue's current bread and butter), but also global heavyweights like Oprah, and of course the cherry on the cake - Meisel. Under him Vogue have acquired some streetwear brands to diversify their advertisers. Last month it was revealed that he's doing a collab with Adidas for London Pride. All these coups will count in his favour. CN may be well aware of all the risk involve and would want to play it safe. The folding of Lucky, Self, and TeenVogue is still fresh. And it's not as if Vanity Fair and Glamour are making strides. To that end, yes, I can see them going for EE with his proven track record.
What I will say is this. Whoever will take over from Anna will be someone with more than just visual, styling or editing chops. That job require a star type editor, which he is as he adore the limelight. Agree with Mon, whoever it will be have their work cut out. Anne is doing great at Marie Claire, Nina is a force with Gan, an upstart like Laura can easily unsettle with her wild card covers (and she's under new management, which means they may have granted her more control)
Personally I'd be more concerned about British Vogue. It can't be good for readers (and advertisers!) to see editors change so soon.
Although if he does go to US Vogue, Lucinda better update her resume, if she hasn't already.