typical way of online wallet scam is that the "website hacked, and all coins stolen".
Sounds so much like inputs.io lol. 
And Bitfloor.
And InstaWallet.
And Bitcoinica.
And a significant percentage of the world's population appears to be incapable of learning from the past experiences of others, so we can expect similar instances in the future.
and Bitcash.cz
as you wrote ... there will be more