IRS was targeting all virtual currencies as being a properties. That would include anything used in WoW, any games in PS4, Xbox One, second Life, nintendo, etc, etc...
This is a very difficult task.
Why it is a very difficult task ? What makes it difficult?
Do you remember the meaning of MT GOX? Do you remember why this platform was created? Do you remember why people were using that platform before MT GOX became number one for Bitcoin?
A friend of mine is a big ultima online gamer for many many many years.
http://www.youtube.com/watch?v=VhDvJ8RketAWhen you start playing you get killed pretty quick as people like my friend have a capital of so much magic power. So instead of working hard for many weeks to get that magic ax, you could simply buy it from him, with real cash $$$.
And although the price of a magical virtual property may not be $300 or more, based on that ruling the IRS would need to audit the whole Ultima Online universe and ask for everyone's profile to see who is making the $$$ and how they collect the money.
There is nothing that would differentiate owning a bit of a bitcoin or a magical flying goat and selling them for profit for the IRS. Now multiply this for every game on every platform that let you "exchange stuff between players".
That would be the IRS's new priority instead of drug money from Mexico being laundered by the Billions every year.