The definition of currency varies from country to country, and also on the era (the definition of currency in 1920 is different to what it is now). And, if you look at a 'traditional' definition of currency, bitcoin and altcoins do not satisfy all requirements
They do not, but as you mentioned, history verifies that. New definitions are made, new technological revolutions are made like with bitcoin.
Money as we know it change with bitcoin on the scene.