I can confirm that I did reinstall FP OS and apparently had G. Apps disappearing (you also get again the widget ‘click here to install GApps’), and this definitely without loosing any of the apps I bought.
Now, most of the essential paying apps don’t go with Google alone, you may find you can also pay directly on the app site (see here, we just started a thread) or via another ‘market’, like Mobogenie etc.