He's the perfect profile but it would be the wrong move imo, anyone on the ticket for 2020 for President or VP should be a current nationally elected official.
It would be too easy for Trump to target him & Dems for getting behind a loser. Someone who lost to Cruz, who lost emphatically to Trump - he'll have a field day with it.
Trump is going to get nasty, and he's going to fight dirty, and the Dems need to be preemptive of this.
I like him a lot though, but he needs to be patient and play the long game now.