4.0 - Existing Widget to App migration?

What is the best way to transition current existing widgets to apps on 4.0?

Should I just use the same app UUID and publish it as an app? But what with the older devices? I would like to keep it a widget for them?

So maybe I should create a new app UUID as an app, and keep the existing one? But then all my ratings & reviews are lost... 

What is the best suggested way to do this?