

Make it the median life expectancy, rather than a fixed, 70 years.
For the court, leave it at a life term, but remove the size constraint. At the end of the first and third year of every presidential term, add one new justice. This moves the appointment process to a fixed time, so there are no surprises.
When a justice dies or retires, their seat is removed, not filled. This ensures that an untimely death swings only one seat, not two.
Since there is no longer an incentive for strategic retirement, the size of the court will increase, probably to around 13 justices. Presidents will want the absolute youngest justices they can get through the Senate.
The larger size means that whatever swing the court does have from deaths or retirements will be smaller and less impactful than it is now.
Finally, any circuit court justice has already faced senate confirmation hearings for their current appointment. Any circuit court judge should be eligible to be elevated to the supreme court without an additional senate confirmation. If the Senate wants to play games and reject all of the president’s candidates, the president has a small pool of candidates that can bypass the additional confirmation process
Cone on, you can do better than that. I believe in you.