I think DRK will able to set its feet on solid land if it holds its advantage over BTC for some amount of time, let's several months.
But if BTC makes possible for true anonymity in the near future, what advantage will DRK have?
I don't think Bitcoin will ever be anonymous.
There is no reason to. The whole point of Bitcoin is that it's transparent and the whole point of Darkcoin is that it's opaque. One isn't better than the other, they just serve different requirements.
Bitcoin's whole infrastructure revolves around it's transparent block chain. There are thousands of merchants now using it. Apart from anything else, Bitcoin would have to go right back to basics and start again if it wanted to implement anonymity. It would loose all the confidence it's gained and all the consolidation it's done over the past few years.
Not ever happening I think.
may be there will be 3rd parties like dark wallet or tor in a way that will fill the gap an offer services to make BTC more anonym... but i also think BTC itslf will not go in this direction