He will likely run and probably get the nomination with Booker as his VP after a lot of internal squabbling within the democrat party 'back rooms'. While the idea of running an "old white guy" at the top of the ticket is not palatable to most of the left wing base, they will need someone like Biden in order to try to regain the Midwest constituency they lost in 2016. Having Booker as the VP will be the compromise in order to energize the black vote that was missing with clinton in 2016. It will also make Booker the heir apparent to the throne in an effort to create obama 2.0, who will be immune from any criticism because he is a "person of color", no matter how much of a train wreck his policies are.
Just my non-scientific hypothesis