First of all, do you really think that three supreme court judges will retire in next two years? Why would Kagan, Sontomoyor, Alito or Roberts retire? They just started. Then if Ginsberg or Breyer retire and get replaced by any of these three what difference does that make? Finally is there any realistic chance that Thomas, Scalia or Kennedy could retire in the next two years? I don’t think so!
Second point: how will any of these three (polarizing) figures that you cite ever get confirmed in the senate where GOP still has probably 45 senators (+2 independents & 11 blue-dog Dem senators from deep-red states ) and filibuster that is alive and working.
United States Senate is the greatest political entity constructed by our founding fathers to keep short-term political extremism in check. I am forever grateful to them for having the foresight to think of it more than 300 years ago.