Any institution can create a form of cryptocurrency.  It does not have to be a large financial institution.  Amazoncoin is one example.  All of these new currencies would require trust in that institution.  These might work with their customers, but it is hard to see they would develop a universal appeal.  For example, why would you go and buy, say AliBaba's Alicoins, JP Morgan's JPcoins or Sumimoto's Sumicoins, which you can't use elsewhere? If they are backed by something like gold, it is still a claim, you would not know if they are actually backed or not.  You are still taking the counterparty risk in financial lingo.

The real threat to universal adoption of a decentralized cryptocurrency comes from the States.  Each State might develop its own currency, may rule it as fungible with their paper currency.  Such as ChinaCoin, Ruscoin, USAcoin....They have the power to enforce the use of these while ruling Bitcoin etc. illegal.