I think this would be a wonderful idea. It is an epic story and the musical has great music.
I think there is a way of animation in feature films that hasn't been done yet. I'm talking about the techniques used in "Paperman", with the painterly quality and structures, but then in color and taken to the next level. Using the best of both worlds. Making it visually stunning, without having that CGI computer look, like Tangled has.
Think of the backgrounds they can create with the pyramids and the rivers. And the character designs of princess Amneris, Captain Radames and Aida.
There are a lot of fun elements in this story, but it's also tragic. I love the idea of the "reincarnation miracle" element. That would work even better in an animated film than in the musical. They could show some magical scene after the burial where they embrace and turn into lights, lights that travel across space and time until they meet the "modern lovers" in the museum, in front of the Tomb of Aida.
This really could be a new animated musical for all ages again, and start a whole new era.
I do think they have to keep it edgy and mature, make it a visually and musically stunning journey, without too much slapstick jokes. A bit like Les Miserables, people love serious songs and sequences that touch them.
Can you imagine the opening scene in the museum when Amneris starts singing and then the scene changes into the ship blasting down the Nile when the story begins?
http://www.youtube.com/watch?v=v_XHTzc6lag