It's already a 6-3 Court, it functionally doesn't matter if Sotomayor dies at this point. Roberts being the most moderate right-wing voice on the Court functionally doesn't matter either, because they can still do 5-4 extreme rulings without him.
The Court is fucked for decades unless it is expanded.
If Democrats are ever able to win again they need to expand and pack the Court. However, that was already true before 2024 and they refused and if they had won in 2024 they would continue to refuse. Democrats do not take this threat seriously.
Kind of a chicken-and-egg problem. The only way Democrats would ever consider packing the Court is if the Court was hopelessly rigged against them (even more than it already was, I mean) but by the very fact that the Court is rigged they might not ever be allowed to win another election because a 6-3 Court would probably let Trump cancel elections.
Basically the whole system is fucked. Tear it down.