Our reseller "assumed" we wanted government (GCC) licensing when we first bought Office 365, and we didn't know better. Now we see all the restrictions and limitations that go along with the Gov classification, none of which we need for compliance (we're a small municipal agency). As of 18 months ago there was no option, but I'll ask again:
Is there a MS approved transition process to move our tenant data from GCC/Gov E1 and E3 licensing over to regular E1 and E3 licenses if we change SKUs at our next renewal?
As of 6 months ago, there still wasn't an option for a Commercial to Government licensing transition (we don't want it anymore though), and I would expect there would be more demand for that than the other way around.
In my opinion, as a SharePoint admin for a large-ish municipal organization, I would not count on Microsoft handling this bridge any time soon, and would advise considering how to consolidate your content to make a manual move to a fresh Commercial tier.