I actually foresee 4 more (assuming of course Trump wins reelection).
Ginsburg of course - likely this year.
Thomas - likely recommending his successor so he can retire.
Breyer will be 81 next year in 6 years that puts him at 87.
Sotomayor who has health issues with her diabetes
That would leave the furthest left as Kagan followed by Roberts. She’s in her early 50s and not likely headed anywhere for a long time.
Next furthest would then be Roberts - who I have some thoughts might leave or be asked to leave by the Q team since he allowed himself to be coopted (imho)
good thoughts reed!