A tale of 2 Windows Phone updates: 8 & RT?

After reading so much misinformation, rumor, and speculation; I began to speculate myself. It just surprises me that so many people are saying different things. There are rumors about current devices not being upgradable while rumors are floating around of people testing the update on Lumia 610's and 800's. What if there are 2 updates coming?

Windows Phone 8 - This update is coming for all current phones. This will continue the trend of being based off of a Windows CE core and maintain a similar code base to Windows Phone 7. This update will offer new functionality, performance, and stability updates to the current OS. This will be the OS Nokia is working on to drive the cost down to be competitive in emerging markets with low-end devices.

Windows Phone RT - A new Windows Phone OS based on the Windows NT core and Windows 8 features with backwards compatibility for Silverlight and XNA Apps. This will be a modified version of Windows RT with a new UI to fit on a phone screen. This is the update that will not be released for current phones and only available on new devices.

I'm not sure I believe this myself but it is an interesting thought. What are your thoughts?

Discuss.

(updated to clarify differences between OS's)