I don't think Karlie will become an Angel. I watched the show last night, and while I can acknowledge that Karlie is a good model, she just doesn't have the body of a VS Angel. Angels are known for having curvaceous figures, and Karlie just doesn't have that right now. All those people saying "Oh, but she has done sexy print work" are forgetting that those pictures are heavily photoshopped.
VS likes her, but if she wants to join the girls doing the main campaigns, she's going to have to wait a couple of years.