> If mining additional Bitcoins at present is not economically viable than Bitcoins are not (currently) a fiat currency.
Whether Bitcoin can be mined or not has absolutely nothing to do with whether it's a fiat currency or not, so your logic does not follow. Fiat doesn't mean "can easily manipulate". Any currency that isn't backed by (value derived from) a hard asset is a fiat currency. Burning electricity to create bitcoin's is not "backed by", that electricity is gone, used up, wasted. Other crypto currencies like peercoin or primecoin address bitcoins wasted energy, but they are all fiat currencies. Their value derives from confidence, not assets.
Whether Bitcoin can be mined or not has absolutely nothing to do with whether it's a fiat currency or not, so your logic does not follow. Fiat doesn't mean "can easily manipulate". Any currency that isn't backed by (value derived from) a hard asset is a fiat currency. Burning electricity to create bitcoin's is not "backed by", that electricity is gone, used up, wasted. Other crypto currencies like peercoin or primecoin address bitcoins wasted energy, but they are all fiat currencies. Their value derives from confidence, not assets.