So to me there are 2 (or 3 options)
a) You make your software compatible (<- best option to me)
b) You give me refunds for GSX (complete as it is not usable anymore) and the new to buy AES credits
for your fsdreamteam-airports I use (40,34 Euro + 59.80 Euro for AES Credits)
c) You give me an opportunity to update my OS (<- how could you do this?)
You omitted the ONLY two solutions that are really available to you:
1) You keep using GSX version you bought.
If the latest version with Couatl 2 worked, you can simply use that.
Nowhere on our site we ever said you are entitled with free upgrades forever, no matter what. YOU have made a choice to use an obsolete and officially unsupported OS, so you must expect that NEW versions of the software you bought might not always work on your old OS.
An easy example you can surely understand:
I have an iPhone 4 that still works fine and has its use, and also iPad 1. However, the iPhone cannot run any IOS higher than 7.x, so I cannot update to the latest OS and, because of this, A LOT of my PURCHASED apps CANNOT be updated to their latest free version, because they have been updated to run only on OS8+. Same with the iPad 1, but even worse, since that one cannot run anything higher than OS6, which means the updated apps I cannot use anymore there are even MORE.
Can I go to Apple or to all the app developers asking for a refund "because THEY changed THEIR software, I haven't changed anything on my side", without making a fool of myself ? Of course not. I'll keep using my purchased app with the LAST version that works, simple as that.
2) You update your OS, which is obviously the only sane choice you can do.
In any case, now that we are out of Beta, we also updated the system requirements on the webpage, to remove XP from the supported OS, but this is really for future customers. As I've said, you can simply keep using the version you bought, if it works.