@cbae: Is it a rumor? I thought WP8 was Windows 8 with the WP7 UI. They've already alluded that WP7 app devs can port their skills to WP8, i.e. Silverlight is dead, use WinRT.
edit: read the article. I have huge doubts that MS would not have an update path from WP7 to WP8. Especially with the Lumia 900 just released. Now, whether or not carriers release that update remains to be seen.