In my experience with digital books and music, namely through the struggling providers known as Zune Music Market Place and the Sony Reader Store, when things folded, when publishers had copy right issues with the companies, depending on the circumstances they either 1. Unlocked the digital media to use on any device I wanted. or 2. Refunded my money when the digital media was removed from my collection.
This is what I would hope video games companies would do too. Fingers crossed they unlock the digital media for customers to continue using if they fold, sell the rights off to another company to publish(in fact, Sear's photography sold the rights of their works to Walmart recently, so customers can continue to get copies of their photos) but at the very least they have to refund the customer.
This whole scenario has been something I've argued with older generations for years now. It is a major cultural change, a different way of looking at the copy right laws thanks to digital media in all of it's forms. In technicalities, it is illegal by federal law to be reselling your used games, movies, music and various arts such as posters/statues/photography. You own a physical copy of something someone else created, it is not yours to resell, remake, or claim as your own, the person who worked hard to create the item should get credit at the very least in the form of a copy right release. That is the nature of copy right laws. You can't spend several hundred on a professional photography, then expect to just go to Walgreen's and make cheap copies of their work. They have to give you written permission to do it, or you've given them the right to sue your ass and Walgreen's. It used to be you had to go directly to the photography for copies of pictures they created for you, yes, they are more expensive than going to Walgreen's, but you are paying for the quality print and work someone created. If you want Walgreen's cheaper price, take the pictures yourself, then you have full rights to do whatever you want. Cause you created it.
The whole reason selling used movies and music aren't a huge thing like used games are, is because buying new is far more affordable, and you would be getting something new, unscratched and untouched by someone else. Still wrapped in a shiny plastic. Things balanced out for those industries. Movies and music are far more focused on illegal digital copies of their works. Video games on the other hand, have allowed the used game market to thrive because they have continually kept the cost of their games above what many people can afford. If they want to kill the used game market, they will need to drop the price of their new games if they expect the customers to start buying new. That will be the easiest way of doing it without inconveniencing and pissing off customers.