As of now, the most likely imo is Virginia Lieutenant Governor Winsome Sears. Sears can run on the Youngkin Administration's extremely high approval ratings in Virginia. She would also have a decent chance of winning, especially if Biden is re-elected in 2024.
I don’t think it’s going to be her. Sears isn’t as popular as Youngkin and IMO would lose. She also won’t be facing a candidate nearly as bad as McAuliffe in all likelihood.
You bring a good point, considering the fact that Abigail Spanberger (a popular Democratic representative, and someone who has the ability to win Biden-Youngkin voters) is running for governor.
But as of now I think she's the most likely. Of course there could be other options in other states that could emerge between now and then....