Discover is unique since Discover Bank is part of Discover Financial Services, but I don't believe that it's owned by DFS. However, since pretty much all Discover Cards are issued by Discover Bank, if Discover Bank suddenly went belly up and totally stopped operations, then pretty much everyone's Discover Card in their wallets would presumably be useless at that point because there's no issuing bank.
Let's just say that if you looked into my work history, you would DISCOVER that I work for the company that plans, designs and runs the web site for a particular credit card company. This is a web site where you can DISCOVER things about a famous cash back program and you might even DISCOVER the company also has a bank. If you snoop around a bit on certain web sites where people Link In to other people, you might even DISCOVER that I was one of the folks who helped with the strategy and planning for that online bank as well as the credit card site and perhaps it would help you DISCOVER more about why I know so much about things in the credit card industry.
Just FYI.
DFS is publicly traded, plenty of info online about them.