I know an iApp can be upgraded to another version of the same iApp. But can I upgrade the Exchange 2010_2013 iApp to the Exchange 2016 iApp.
Note: the customer says they are going to use the same features in 2016 that they did in 2010. The current OS is Exchange 2010 and they are migrating to 2016.
The Exchange 2010_2013 and Exchange 2016 iApp are separate, unique, iApps from one another which is why you cannot do a "normal" upgrade from 2010_2013 to 2016.
When you import the 2016 iApp it is an entirely separate and unique iApp in the F5, it will not overwrite the 2010_2013 version or upgrade it.
The upgrade path would involve undeploying the 2010_2013 iApp then deploying a new instance of the 2016 iApp.