We'd probably be dealing with incumbent president Evan Bayh so there'd be no 2020 Democratic primary worth looking at.
You don't think Clinton would have ran in 2016? Evan Bayh didn't exactly inspire many Democrats in the 2000s. If he did try to run I think even after two terms of Obama he wouldn't have been that strong a candidate in the primary
Hillary had initially ruled out a 2016 bid, likely because she thought Joe would run
She
publicly "ruled it out" early on so as to not appear as if she thought she was entitled to the nomination. She was never not gonna run, though.