i would expect before the SCOTUS gave up too much authority along the lines of
NO confirmations at all, they would declare the 60 vote rule unconstitutional
This still doesn't address the current situation where the GOP Senate can vote down any USSC Obama nominee by a simple majority vote.
This would still leave us Constitutionally with eight Justices, which has occurred in the past.
Tie votes would revert back to previous court rulings, effectively ending debate.
the senate won't refuse to confirm *someone* because each party has a (roughly) 50/50 shot at president and
they don't want the favor returned once they have the white house.
In the end, the other two branches lose even more power
Either party could filibuster a USSC nominee in the next Presidency--depending on who owns the Senate and Presidency.
We have not seen the "Nuclear Option" used yet for USSC appointees--that looks like the only way we'll get a ninth Justice in the future.
68 of the first 96 nominees of our NATION were approved by a voice vote.
Beginning with Thurgood Marshall in 1967, the last 21 approved Justices were by roll-call vote.
Thomas got the least number of votes in Modern times--52; followed by Alito with 58.
As you can see, a filibuster by DEMs could have stopped them.
It will take years for the legalities of the filibuster to reach the USSC.
IMHO, Roberts/Kennedy rulings will lean right on changing the way Congress works, leaving the filibuster alone.
We may well have a reached a point in our miserable partisan history in the Senate both ways
that both the Senate and President must be of the same party just to get a new Justice .