Plus with the internet, things don't just get lost anymore. Everything that's been released is going to be around for as long as there's an internet.
I think you're reversing the argument here: the internet is actually a very volatile place with regard to storage, much more volatile than the physical archives in which classical music is stored. We still have archives full of classical music that has never even been performed, chances are this will not be so for rock music in 200 years unless someone starts a humongous "data tank" and really makes sure nothing is lost. Sure, the most popular rock will survive, but when we look at music history mere popularity is rarely a good indicator of lasting value.
I think the biggest factor which may prevent the survival of contemporary popular music may be the fact that pop/rock/funk etc. are very much tied up to the actual artists. You don't need Brahms to play a Brahms symphony, and in fact even back in the day classical music was often performed without the actual composers being there. However, you need Paul McCartney to play a Beatles song, and you need Axl Rose to play Guns 'n Roses. Sure, you can start a Beatles cover band, but A. who would go and see that? and B. it simply will never sound the same. Performance is what keeps music alive. Jazz is already encountering the same problems: sure you can cover Coltrane but is it really the same? I think this is one of the factors why classical music is still so relevant.
Classical music is overhyped. Most of it was written to a certain standard with very few pushing boundaries (those being the ones we remember most today). Just like how music is written now.
To a certain
very high standard indeed. You might not like classical music, but to say it is overhyped is a falsity. Don't forget that we owe almost every element in modern music to classical music.
Sure music is simpler now, but that has more to do with the way technology has evolved more than anything else.
I think that would actually have more to do with most current composers lacking the compositional skill to write anything else than very simple music. Could John Lennon have written a good fugue? Could Slash compose some proper counterpoint? Me thinks no.