I don't think DRK will outright "replace" BTC, but I think they'll be looking at each other eye-to-eye in the near future...

I think Bitcoin is going to remain a very popular and sort of "mainstream" crypto-currency. Whereas Darkcoin is going to provide a global financial system for anonymous, private transactions -- the world's first global "dark currency market". Bitcoin and Darkcoin will co-exist for quite some time and have a symbiotic relationship. And I think you'll see people in the future swapping large amounts of BTC for DRK and back into BTC after using Darksend to anonymize their Bitcoin activity... essentially making DRK an anonymous on-ramp/off-ramp for Bitcoin. You'll probably also see anonymous banking, anonymous stock/futures/FOREX brokerages, dark exchanges and all sorts of awesome privacy centric financial infrastructure spring up around Darkcoin.

With Darkcoin being a bit more "exotic" than Bitcoin, a lower coin supply (for now) and high demand, I think 1 DRK might trade at 1.5x to 3x the value of 1 BTC but Bitcoin may retain a higher total market cap for some time...

-- The DRK Lord --