There haven't always been nine justices on the court. The U.S. Constitution established the Supreme Court but left it to Congress to decide how many justices should make up the court. The Judiciary Act of 1789 set the number at six: a chief justice and five associate justices.Oct 8, 2013
history-lists/7-things-you-might-not-know-about-the-u-s-supreme-court
So if now hot potato issues are being ruled on by the supreme court because there is a 4 to 4 split, then only on true issues of consensus will the Supreme Court Rule, and if the Democrats believe the action for one year of not appointing a replacement for Scalia will allow them to sandbag any appointment at all, which means the status quo remains, then there is a very good chance that the court will run with eight, seven, and even down to six members depending on the compromise which can be crafted. The status quo will remain on the court for four years, the Republicans will do the same thing to the next president, until a political compromise is reached......bet on it.