A huge influence of mine, Paul Sztorc of Truthcoin/Hivemind has this to say about Cryptonote/Monero here
http://bitcoinhivemind.com/blog/chance-of-success/This was asked in comments
Q
Hey Paul, love your work. On your opinion chart, what would you rate the chances of cryptonote currencies like Monero? Closer to ZeroCash(60%) or other altcoins(0.01%)?
A
I would say closer to ZeroCash. I've heard from the relevant experts that Monero is not computationally-efficient enough to stand on its own, but I have similar problems with ZeroCash standing on its own (it is almost "too private", for people to check and make sure it's working correctly). However, I think both (and/or, the concept of "coin privacy") will be among the first practical, usable, sidechain applications. I think that people will sidechain coins over, mix them on the sidechain, and then send them back.