I think it may be DARKCOIN! It may take 1 yr or 2.
Blackcoin said the same thing not so long ago (I once believe it could, because of PoS). Maybe NEM, maybe Sharecoin. Maybe Monero. But certainly not Darkcoin (because Monero is better at everything Darkcoin is doing and Zerocash
might be even better for the anonimity part). And two more reason why darkcoin won't replace BTC: first because such a name is an invitation for public refusal and because tracability is required in a lot of things (like public spending), so an anonymous crypto would not replace a traceable crypto.
what is NEM?
NXT done better. Fairer distribution, more features. It has not been released yet, some stakes will be auctionned since the initial several-weeks IPO is over.
The "market cap" of the top 100 alts together are not even close (<10%, and from this 10% LTC takes 5%) of the BTC market cap. Apart from NXT (and it's clones) none of them offers any significant improvement over bitcoin.
You forgot about Cryptnote-based coins (Bytecoin, Bitmonero, Monero and HoneyPenny and probably much much for in the future since Cryptonote is so much open-ended). Plus, NEM is not a NXT clone, even though its initial goal was to be a relaunch with fairer distribution (I can't talk for the other NXT "clones").
None of the alts have any significant real world services (you can't even buy a single banana or a gallon of petrol for DRK). Until an alt doesn't have good services - good means services what you need in you daily routine - all of the stuff above are just dreaming.
Agree. The financial world seems to forget that primary use of a coin is not to make them rich, but to be used by the 99,98% of the population that is actually doing something useful.