If Biden were looking to replace Kamala Harris by nominating her to the Supreme Court, that would mean he’d have to hope for a vacancy before the 2022 midterms.
Even if that happens, the 50-50 split in the chamber means that he’d have to get at least one Republican to vote with all the Democrats, and that is assuming that she’d have the support of moderate Democrats like Manchin and Sinema.
As a hyperpartisan San Francisco liberal, it seems unlikely that either would risk voting for her confirmation to the Supreme Court over an actual jurist with experience on the bench.
A vacancy after the midterms would be even more problematic. The current political climate suggests that the 2022 midterms will be very good for the GOP.
Thus, should a Supreme Court vacancy occur after the 2022 midterms, Biden will likely face a GOP majority. Mitch McConnell has already promised to block Biden from filling a vacancy if the GOP wins the Senate. Still, even if he goes back on that, it seems unlikely that Kamala Harris would get Republican support, thus dooming her nomination.
It is possible that Breyer could retire after the current term. That would mean sometime this summer at the earliest, there could be a vacancy. If Biden were to nominate Harris at this point, it would be such a political superstorm that McConnell would certainly put a hold until after the elections.
So for this scheme to work would require several rolls of the dice turning up 7.
Who does he expected to be murdered.... er... die conveniently of TOTALLY natural causes?
Biden could appoint her and if she accepted the appointment, she would have to resign as vice president. As soon as her resignation was accepted, a vindictive Biden could withdraw her nomination. This would leave her out with no recourse. Biden has no future so he would have no concern about the fallout.