John Roberts closed his opinion in King v. Burwell on a note that has liberals hailing the end of the right wing’s judicial assault on the Affordable Care Act. The ruling was crafted to settle the question of the law’s valuable insurance subsidies once and for all, and contained a note of conclusiveness, verging on fondness for Obamacare, which has to be read as an admonition to the law’s attackers to seek redress elsewhere.

“[I]n every case we must respect the role of the Legislature, and take care not to undo what it has done,” Roberts wrote. “A fair reading of legislation demands a fair understanding of the legislative plan. Congress passed the Affordable Care Act to improve health insurance markets, not to destroy them. If at all possible, we must interpret the Act in a way that is consistent with the former, and avoids the latter.”

So long as Roberts is the deciding vote, the Affordable Care Act—whose lineage is no mystery to conservatives—will not be damaged by litigation that seeks to undermine it. This is a huge relief to the law’s supporters, who correctly sense that the right’s appetite for frivolous Obamacare lawsuits is bottomless. But it shouldn’t be allowed to give rise to complacency. The Roberts Court is still plenty conservative, and has the potential to become more so in the years ahead.

If you look at the totality of Roberts's career, and his decade as a Supreme Court justice, two trends emerge: Roberts is exceedingly business friendly (he described the issue at stake in King as “a question of deep economic and political significance”); and is deeply animated by a set of issues—limiting affirmative action, voting rights, campaign finance regulations, abortion—that by pure luck seems not to include universal health insurance.

The Roberts Court has already done lasting damage on several of these fronts. Nothing inspires spasms of rage on the right quite like Obamacare, which explains why the conservatives feel as if Roberts has betrayed them on a Shakespearean scale. But across a broader array of issues, Roberts has proved himself, The Atlantic's James Fallows notes,  a “shrewd strategist … who knows how to pick his battles rather than getting mired in obstructive pandering to the base.”

Outside the four corners of Obamacare, the left is still vulnerable to what you might call a Federalist Society problem. Conservatives are furious at Roberts, but at some level they still understand that his Court can be a useful tool. The ideological balance on the Court, and the simultaneous dysfunction of the political branches, has created a powerful incentive for conservatives to litigate federal regulatory laws, and accorded them a decent chance of success.

If that sounds alarming, it has the potential to get much, much worse. If a Republican wins the presidency in 2016, he will almost certainly appoint a sixth conservative to the Court, and perhaps a seventh. The firewall currently protecting Obamacare could easily fall, and what under the current regime would yield a 5-4 victory for liberalism will become a 5-4 or 6-3 defeat. In their mourning, Obamacare’s legal antagonists will pressure Republican presidential candidates to promise to nominate the kinds of justices who think most of the 20th century was wrongly decided—think Clarence Thomases, rather than John Robertses. Add two of them to the Court, replacing two liberal justices, and they will have the power to do incredible damage.

For a Republican president to repeal, modify, or replace Obamacare legislatively, Republicans in Congress would probably need to eliminate the legislative filibuster, generating a great deal of controversy. Eliminating the filibuster for Supreme Court justices will generate much less controversy, because Democrats eliminated it for all other presidential nominations when they last controlled the Senate. (I personally would not object to eliminating the filibuster, but there’s no denying that, if preserved, it would serve as a powerful Democratic bulwark against conservative dominance in 2017. For that reason it will be eliminated.)

This judicial threat to liberalism won’t subside, either, until a future Democratic president replaces one of the Court’s existing conservatives with a liberal. The Roberts Court would give way to the Kagan Court, and the right would devote fewer resources to pursuing their agenda through the judicial system. But until then, pretty much everything President Obama has accomplished should be considered at risk, even if Obamacare is safe for the moment.