The LBJ 1968 situation was radically different—lets look at the primary season prior to his withdrawal:
New Hampshire March 12: LBJ (write in) 50% McCarthy 42%
March 16: RFK announces he will challenge LBJ
March 31: LBJ withdraws after polls in Wisconsin showed him at 12%
https://en.wikipedia.org/wiki/1968_Democratic_Party_presidential_primaries
Flash forward to today—there are no serious challengers to Biden on the Democratic side:
Let us look at the polls—nationally Biden has 70% support of Democrats and the trend has been stable for months:
https://projects.fivethirtyeight.com/polls/president-primary-d/2024/national/
Biden won New Hampshire easily with write ins.
Next up—South Carolina—polls show Biden at 69%.
Conclusion: The numbers say that Biden will be the Democratic nominee.
Anyone claiming otherwise needs to produce strong evidence for their claims. Imho they have failed to do so to date.
On the other hand, as I've said multiple times now, the average RAT voter is quite pleased with his administration because they are getting everything they want so they're fine if he stays where he is. The only malcontents at the moment ar the Hamas hordes from hell because they want more Israeli blood than Biden has given them to this point. If he were to stop all aid to Israel, they'd be on board as well.