With Obama as president, that assures the balance will slant to a 5-4 liberal majority, and a push to advance a liberal agenda by activist-liberal fiat, rather than by the Constitutional standard. Ruth Bader Ginsberg and Sonia Sotomayor have both made comments and actions that make their scorn for the Constitution in favor of their own agenda quite clear.

After 8 years of no accomplishments and ramming things through as executive orders rather than rallying consensus and passing laws, Obama finally has a chance to have a legacy after his presidency ends, through his good fortune of being able to appoint another justice, who will give liberals/Dems their partisan majority. (As opposed to a conservative majority that respects the Constitution and the rule of law over their own agenda.)