I got hold on a bunch of classic PC games that where 10+ years old and lots of the CD's had data errors, so I wouln't bet on disc burning although plastic can last a long time so it has potential, maybe a startup idea, burning family albums on special bluerays that will last a long time =) also the lasers get old as well, so there might be difficult to find a working blyeray reader 50 years from now, but just like the environment it's not our problem right now :P