Hopefully they will bring them back. I just looked the tab is still there. I think if they were going to discontinue them, you wouldn't be able to see they were out of stock or the link to get to them. You could email them: support@help.disneymovieinsiders.com
Gift cards go in and out of stock. There are times when gift cards are not an option. It's nothing to worry about. Be patient and wait. The gift cards will be back eventually.