There's nothing government would rather do than to ban cash, with the exact same arguments. Heck, bitcoin has only become successful because it emulates the properties of cash in the virtual world, which is dominated by traceable transactions like credit cards and wire transfer.
So this is really just shooting yourself in the right foot, when they shot you in the left.
You seem to think Bitcoin is like cash because it's untracable. That is not true. Bitcoin is 100% traceable, just like credit cards and wire transfer, and maybe even more so than those two. Thanks to the block chain, everybody knows every single transaction that has ever been made in the world. Sure, you can't directly link a Bitcoin address to a person, but I'm sure there are plenty of ways to do so. Security researchers managed to link an anonymized Yahoo search entry to a specific old lady living in a specific small town. I'm sure similar techniques can be applied on Bitcoin addresses, analyzing transaction patterns, to link them to specific people.
So this is really just shooting yourself in the right foot, when they shot you in the left.