I just can’t imagine it. Harris knows she moves up to the big seat, or she goes nowhere politically… ever. If she holds out she has, I’d say, at least a 50% chance of succeeding to the presidency before 2024. Why would she leave?
As my ggdad would say, everything is 50-50, it either happens or it doesn't.
However, looking at the dessicated Joe, Kamala won't have to wait 3 years. And for sure she'd rather have her current job (worth a bucket of warm spit, so I've heard) than a seat on the SC. Justicing is hard work. She doesn't seem the type. Presidenting means lots of applause, glory, travel, and opportunities to spout off to friendly media. After one term she lives and parties like an Obama.