In the PDF files and interviews Yoshida mentioned something about Legendary weapons. Like the Excalibur, Masamune and such. If those do ever come out I imagine they will replace relics? Either that or maybe they will add more and more quests to relics to upgrade them to Legendary weapons Who knows?

http://rainyautumnskies.wordpress.co...naoki-yoshida/

and here

http://gdl.square-enix.com/ffxiv/dow...Content_EN.pdf

I have no idea if this means they will be upgrading relics eventually or maybe new weapons entirely Interesting though either way !