A clear and astute analysis. I agree entirely that the Democrats need to upend the dysfunctional gerontocracy by encouraging Biden to retire, and selecting a fresh new face--whether Kamala, Gretchen Whitmer, Gavin Newsom, or whoever, it doesn't matter.
An open convention will lead to the typical floor fight, even multiple ballots, but it won't be toxic like 1968 because there is no Vietnam war, no deep schism in the party along those lines. And the winner will have to actually win the hearts and minds of the delegates.
If Biden thinks that a frail, amiable guy like him can win against the swaggering thuggishness and toxic charisma of Trump, he is delusional. If he stays in the race, I fear the worst, for if Trump wins, the former USA will become the Fourth Reich!