I understand the politics about calling something a tax, but the penalty for not buying insurance (under the mandate) sure acts like a tax. And it seems everyone agrees that Congress has the Constitutional right to tax. So in the end this whole thing could be struck down because Congress, who has a right to tax, enacted a penalty that acts exactly like a tax but just didnt call it a tax.
One of the litigants argued that even if it were considered a tax, it would be a capitation ("per head") tax under Article 1, Section 9, and not an income tax allowed by the Sixteenth Amendment.