He has repeatedly said that he plans to nominate a Black woman, so that should really be a prerequisite for any list of potential suggestions. Ketanji Brown Jackson (who was on the Garland shortlist back in 2016) & Leondra Kruger will probably top the list.
If I was on Biden's staff, these two would be immediate frontrunners. Both highly qualified, and very smart. Haven't heard of any other potential nominees that fit the black + female qualifications set out by Biden. At least, no others that are also young enough to serve for decades.
For anyone wondering Jackson is 50 and Kruger is 44.
Well, there are some others: Cheri Beasley (54) & Adrienne Nelson (53), for example. But yeah, not many.
Leah Ward Sears is another who could probably actually get past a Republican Senate