Yes, the IRS has already succeeded in taxing Bitcoin. It's to be treated as capital gains, as with any other asset. I prefer
Australia's approach of officially not taxing digital currencies.
I'm happy to read that "Republicans in Congress sent a sharply-worded letter that suggests the tax agency is overstepping its powers." Letter attached as a PDF to this post.
The IRS should lose this battle with Coinbase, and rightfully so. It's fine if the IRS need to subpoena a specific person's tax records because they have probable cause, but asking for
big data dumps oversteps their boundaries.