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.
Most people would never pay taxes if they can avoid punishment. I have seen the proof of that in reality in 90th in Russia.
Differerence than transaction in cash is the same as transactions in golden coins in middle ages. Perhaps you remember that there were some issues with taxation and the property tax was basic. Role of banks also will change as people will not need banks anymore for transactions. So nobody will report about transactions.