Bernie would have lost a national Presidential election in a landslide and the Democrats knew it. They made the right choice.
Hope not. If she were the Democratic nominee and running against Trump I'd hold my nose and vote for her like I voted for Hillary in 2016.
The Democratic Party is probably hoping Trump will run again. If he doesn't, Nikki Haley would likely pull in a whole lot of moderate and suburban women votes in 2024. But Trump is of course a sociopath and won't be willing to step back from the spotlight and let that happen even if he's not running.