"It is literally impossible to “change” the hashing algorithm in Bitcoin; any change would constitute a change in the protocol, and thus result in a completely

"It is literally impossible to “change” the hashing algorithm in Bitcoin; any change would constitute a change in the protocol, and thus result in a completely new currency." This was something that came to my mind some time ago regarding Bitcoin, but I wasn't sure if it was possible, or at least practical. What's to stop other interested parties from changing the protocol/hash and creating myriad competing virtual currencies? Metacoin, Hashcash, Bitcoin++, Digidollars, Ameribits, Eurobits, Digigold, Ingots - you get the point. "Hi, my name is Fred, and this is my currency." We live in a world with a wide range of currencies and exchanges, so I suppose there could just as well be an exchange that supports as many digital currencies as could ever be conceived. But couldn't that also mean that Bitcoin could be devalued through confusion and obfuscation, its present reputation notwithstanding?