I doubt if bitcoin really resembles RTGS; for one thing there is no central agency involved. Or may be it does if you consider distributed network of nodes which does "proof of work" for your bitcoin transaction as a Central Bank
The question, then, is: "is this sufficient"? Do we believe all Bitcoin transactions would be transacted over this system (i.e. over the blockchain) in the future or will we see aggregators akin to DNSs?
I see the work of Mike Hearn and others on micropayment channels as innovative examples of what a DNS for Bitcoin might look like.