"When one's candidate has reaching the point of having virtually zero probability of amassing the delegates necessary to win the nomination.."
How about when TWO candidates have zero probability of amassing the delegates necessary to win the nomination?
NEITHER can get the necessary votes. There is no rule saying go with a plurality of delegates. If anything it should, and I think will, go to the popular vote. That's where it gets messy because while we obviously can't count delegates for FL and MI, a good argument can be made for counting the popular vote for FL. MI is difficult but I would give the 40% "Other" votes to Obama and give Clinton the 60% of the vote she won. Again I'm talking about the POPULAR VOTE, not delegates.
Obama could have ended this months ago. He's not a finisher.