Finally, you can see the SQL 2016 RC3 Evaluation Edition was able to be upgraded to SQL Server 2016 GA.
I was also able to change this from Evaluation Edition to Developer Edition as well.
I am very unlikely to get $$ for Std, and the app works with Exp, so I'm looking into that path.
Is this at all doable for a guy who once sat next to a DBA on a bus?
Currently, this isn’t specified in the SQL 2016 Release Notes. I am not a SQL Server MVP so I have one sending a message to their message board to see if we can get confirmation on if this upgrade will be supported.