With the launch of Outlook.com today, you should be aware of a few changes that will be coming down the pipe if you currently use another Microsoft email service such as Live or Hotmail.
The good news is that your domain is not going anywhere, but Microsoft believes that the Outlook interface is the best on the web and it will eventually be rolling out to all of its other email platforms; this includes any domain that is currently using the Hotmail experience today.
If you like your current layout and do not care for the new Metro design, then you may be out of luck as Microsoft is going to be implementing the UI across all of its properties. The date when this rollout will occur has yet to be announced but know that it is planned for the future.
Metro is Microsoft's future, so the news should not come as a surprise as Microsoft works diligently to implement the UI across all of the company's properties. The company's goal is to have all of its products embrace the Metro design language, so it's only a matter of time before Microsoft is all Metro.