Code:
As long as modules do not contain functions dependent on the authors' servers remaining online then there really is no problem. X-Cart only needs to do one thing - provide a certification badge for modules which do not rely on any type of communication with the authors' servers. Other than this, its buyer beware and you should have been more careful jumping from a one man show right to another.
It would be better if QT could provide a minimum level of certification which also included access to encrypted code if a vendor disappears. Sometimes "one man show" is the best/only option. Perhaps we can find a way for the "one man show" to demonstrate that they have exercised provisions in the event that they have to disappear.
Here is a suggestion
I assume QT avoids a certification program for 3rd parties because of all the work/cost/liability it could mean for them. But if they could come up with some minimal set of certification that does not leave consumers totally stranded, that would be a good first step. If they won't - it might also work to make it a condition of advertising products on this forum that vendors have a plan to execute in the event of their disappearance.