Why kill what is essentially a totally traceable system of currency. Every transaction is recorded for the entire existence of bitcoin.
Do you think there will be any taxes in bitcoins?
Eventually? Yes.
I am able to hide any my transactions in bitcoins. Nobody can oblige me to pay any taxes based on that. Only property taxes will be possible.
How is this any different than transactions in cash? You can take a risk and avoid reporting cash transactions (or bitcoin transactions), but if you get caught the penalties will be stiff. Most people will fulfill their legal obligations as report their income and pay taxes on it, just like most cash businesses do.