A thought I haven’t seen offered much, but could give Biden an ego-soothing role instead of being put out to political pasture - a Harris:Biden ticket.
She gets to be the energetic go-getter at the front (that the Maga hate-oil salesmen are shrieking about atm) while Biden can play the ‘elder statesman’ role of advice and experience to Kamala instead of running himself. You defuse a lot of the competency/decline arguments against Biden, and gird against one of Harris’s biggest threats - her lack of international experience.
Kamala is not a political unknown, but Biden is losing/equal right now to Trump with the DNC money & publicity machine working for him the last eight years. I’d argue Harris has a better shot if those efforts are swung her way. I don’t like Harris, but needn’t convince me to vote team blue - it’s the ~9% undecided we need to convince.