For now, there is no information whether other carriers in the United States would also offer the device when the exclusivity contract between Nokia and AT&T expires. However, it seems like the Finnish smartphone-maker is now up to tying knots with several carriers to carry its devices. For example, T-Mobile would be offering Lumia 810 and Verizon may also carry Lumia 822.
It is possible that other carriers will be offering Lumia 920 six months from now and if so, there would surely be new models with new features. Here is one of the training videos leaked online. If you want to watch the rest, click on the link at the end of this post.