But, people should not rely solely on a third party solution for their archival needs. They should always have a copy of their data that is offline, and physically in their possession, in a ECMA-379/ISO-10995 certified format that will last a long time. Certified Archival Media, is precisely that - it's designed to last on the order of a 100 years or more with zero requirements to validate. If you are super paranoid then you could make two copies. Then, you have both of your bases covered; You have something you can touch, and is 100% under your control, and, simultaneously, Longaccess will take care of all of the hard work of checking integrity, reproducing data, transferring it from data system to data system (in whatever form that takes over the next 30 years), and otherwise ensuring that there is continuity of data which can be accessed by the user (or their descendants) from something as simple as a certificate.
And yes, I do agree that the achilles heal of DVD Archival Media is the very real possibility of there being no DVD players in 20-30 years from now. Here's hoping eBay is still around. :-)