So I hope you make the "old" installer available for your customers still using Vista.
As I've said, if you downloaded the installer when Vista was still supported, you can block the automatic download of the latest version (which doesn't support Vista), by running the GSX installer with the network cable disconnected or the network disabled in the settings.
You can´t expect to buy a new car when you get no more spare part for the engine, I think you will also change the brand of car.
Well, since it's the OS itself which is not supported anymore, I guess if you want to stick to your car analogy, if you really want to change brand, because Microsoft stopped to support Vista, you should switch to Mac OSX.
And, to continue your car analogy, if you suspected your OS would be unsupported soon (Microsoft announced EOL support for Vista years ago), you should keep your "spare parts" ( which is the previous version of our installer ) in a safe place.