Lifetime appointments are the problem not the method of appointment.
You might lose some expertise, but on the other hand, you don't have the tragic spectacle of Justices dieing in office whilst waiting for a 'safe' time to retire.
Taking again Germany as my example, since I know it best: There are 16 judges with a period of 12 years. Adding the age limit and other reasons that averages to about 2 elections per year. Thus a bit more than 4 years till a new group can take over the majority. (Now they are elected alternating by the different chambers of parliament, where one of the chambers, Bundesrat, is also slower moving in replacement ... making it hard for a short term movement to take over control and if, impact is relatively short - unless they stay in power long enough to replace all.
Let them serve for a limited period of time, say 16 years max. Can't be removed before then. It's not that complicated and would prevent justices who literally sit on the bench until the day they die.
I think Germany got that better: here we have a 12 year term (thus a single government can't easily swap them out - a learning from the time of 1933) and a max age of 68 (for whatever reason that was picked)
If that were the case, and justices' terms started in January of even years (to avoid the election cycle), we would currently have 2 Trump appointees, 4 Obama appointees, and 3 Bush appointees, roughly matching what the balance of the court would be next month if Ginsburg had died 3 months later.