Unlikely to be implemented if you ask me. Capital gains are taxed in the US and I do not see why they would find bitcoin capital gains any different from other investment vehicles; in fact it will be very unfair that bitcoin as an asset class does not get taxed. One of the disadvantages of being subjected to US law I suppose. Mind you not all countries have a tax on capital gains, for example Singapore has no capital gains tax no matter what asset class. It just depends on how "friendly" a country want to be with regards to investments.