I very recently purchased rxp gtn750/650 package for xplane and only now realised this issue with the nav data. Although I should have researched this further before purchase as I didn't see anything on the store front about this being a problem but I understand it is my responsibility to do my due diligence.
For now I can only hope we get some sort of compromise in the future (wishful thinking I know but I am an optimist at times) from Garmin or maybe Jeppesen, maybe even some agreement with Navigraph may come about (which is very doubtful I know) to allow an affordable means of accessing the up to date nav data on regular basis. I will be keeping an eye out on the thread for any potential solution that may come about.