They won't nominate the guy who was gonna put people back in chains. For all the talk of unity, Democrats made very clear what they think of anti-Trump Republicans in the 2022 primaries. It's not good.
Though she'd be a good candidate, Granholm can't be president, because she isn't a natural born citizen. Buttigieg is a sharp guy and a good communicator, but he has some stain from his time as SecTrans. And are blue collar types in PA, WI, and MI and Muslims in Dearborn ready to vote for a gay guy? I'm not so sure.