I personally think the Relic weapons will be at least equal to the Dreadwyrm stuff by the time 3.0 drops, if not slightly better depending on itemization (like Nexus was over HA). That being said, I also expect the Relic weapon questline to end upon 3.0 being released and a new weapon quest being started there that will be better yet.

Nothing stays BiS forever, but the Relic line does remain as an excellent filler/perhaps at the time BiS weapon for everyone. I don't really think you can compare the Relic line to the Raid drops given the differences in obtaining them and their place in everyone's gearing. Evolving weapons are fundamentally different than static Raid drops.