This commentary Ian Millhiser gave to USA Today in October seems relevant today:

Many experts foresee three scenarios for the next Supreme Court nomination battle: Either a Senate controlled by the president’s party confirms the nominee by doing away with rules allowing the minority to filibuster, or a Senate ruled by the opposition forces the president to name a moderate or blocks any appointment until the next election. That last scenario could leave the court with only eight members for a protracted period.

“It’s very likely that that seat just stays vacant until there’s unified control” of the White House and Senate, says Ian Millhiser, senior fellow at the liberal Center for American Progress Action Fund. Blackman, a conservative, agrees. “We should be prepared to consider leaving a seat vacant,” he says.