There is no reference to version of nav data. Only a reference to what packages should be loaded. I believe we a overthinking a very simple change in the content.xml.
Package name=“fs-base-nav” active=“true”/>
Package name=“navigraph-navdata” active=“true”/>
Perhaps there’s something else other than the content.xml that the installer change?
If it’s as simple as adding a reference point to the content.xml with those two lines. Then anyone can practically do it manually without actually having a navigraph subscription.
You would still need a subscription for the data. The integration into MSFS is not what you are paying for. I have been using Navigraph for years and their integration into various products is a service and entirely up to the developer. Just because an aircraft (as an example) has built in support for Navigraph data does not mean you get the data. (Although the developer will often supply an out of date AIRAC along with the aircraft).
The changes in the XML is simply to tell MSFS what data to use.
Yeah, but there’s a potential of having just one subscription, and have the data shared across many people. Or even just have the subscription for 1 month of every year. And you’ll still get navigraph data even though it’s slightly outdated whenever a new AIRAC cycle is released.
It is common to have out of date data. Lots of users have bought one cycle and that’s all.
PMDG was a perfect example from years gone by. Everytime you fired up you would get the warning that data was out of date. Didn’t stop you from flying.
Wow, PMDG. I’m glad there is someone else who remembers it. Whatever became of that old fossil? I wonder if anyone is still playing it. 
They are currently developing new study level aircraft for MSFS. Would hardly call one of the premiere aircraft developers in the flight sim world a fossil.
I even put an emoji after my comment and you still can’t see irony?