Sounds like it means the Court will be asked to rule on a narrower, more technical question that bears on the legality of ObamaCare.
The Court was not willing to summarily throw the whole mess into the garbage can. They did, however, (IIRC) signal their willingness to look at individual aspects of the law once those aspects had been argued through the lower courts.
There are many of these aspects, and this one is important because it goes to the issue of what is a tax. This question, as I understand it, brings Constitutional issues into the discussion.
Also keep in mind the "non-separability" aspect of ObamaCare. If any one piece of it is excrement-canned, the whole thing goes down the chute.
Unless the Executive branch decides to ignore that. Then it will take years to go through the courts on that matter.