Speaking of Tammy Baldwin, she has a lot of things going for her to be a contending candidate for 2024. She's boring and inoffensive, like Biden is/was, and moderate/center-left voters like those safe, boring characteristics in a politician. Yet, on public policy, she leans towards progressives and the left with her support of Medicare For All, labor rights, Citizen's United/money in politics, Green New Deal, etc. She is solidly progressive, without appearing as a leftist to the average voters. She also doesn't have the reputation of calling herself a democratic-socialist either. She is also a box checker from a demographic standpoint being both a woman and a lesbian woman apart of the LGBTQIA community. Baldwin also does something that few progressives running in statewide elections usually do, she wins and does so by large margins. She also does better than most Democrats in rural communities and among non-college educated voters.
If Biden doesn't run, Baldwin would be wise to throw her hat in the ring for 2024.