Nullification really is the only option that I can see. Senate only needs 51 votes to repeal Obamacare, but they will never do it, not even with a Republican majority. Hiding behind supreme court decisions is a great way to avoid confronting hot button issues. As with Roe V. Wade, we'll be told that the solution is to appoint a majority of conservative supreme court justices to overturn the Obamacare decision. This will never happen of course, thus giving federal lawmakers the luxury of avoiding the issue forever.