Well, I think it all depends on what you mean by "chance." I mean, if we're playing an American football game, and I'm up by 55 points, sure, you can say "I still have a chance if I can just get 56 more points!" But if I point out that there are 15 seconds left on the clock, it's sort of reached the point where "I still mathematically have a chance" is just lying to yourself.
We can try to come up with a similar argument;
Suppose that in all remaining primary states, Bernie gets the vote share he got in his best primary state excluding Vermont--that's 61%. Suppose that in all remaining caucus states, Bernie gets the vote share he got in his best caucus state--that's 80% (rounded up, to favour Bernie). Suppose that the unpledged delegates break in proportion to the pledge delegates, and so getting 80% in a state gets you 80% of the state's delegates (this is an assumption that favours Bernie, because as Bernie supporters have complained, unpledged delegates undermine the will of the people by supporting the establishment candidates!!!!) So these assumptions are very generous to Bernie.
So, then he earns:
80% of the delegates in USVI and ND for a total of 28
61% of the delegates in PR, CA, MT, NJ, NM, SD, and DC for a total of 547
This gives him a total of 575 more delegates.
Hillary gets the remaining 349 delegates.
The current delegate amounts are:
Hillary 1770 + 349 = 2119
Bernie 1500 + 547 = 2047
So under really the best case scenario assumptions to favour Bernie, he still ends up 80 delegates behind Hillary. Hillary is at this point well over a majority of delegates. If we assume the remaining superdelegates break for the majority winner of the pledged delegates, he loses. If we assume the remaining superdelegates break in any proportion for Hillary he loses. If we assume the remaining superdelegates break entirely for Bernie he loses.
Which means the math goes to some elaborate scheme to flip superdelegates who have already pledged to support Hillary.
So yes, I think we're very much in "I expect to get 5 touchdowns in the last 15 seconds" territory.
I don't think Bernie is going anywhere as long as Hillary's chances of being indicted remain nonzero. If the FBI does release their report and not recommend indictment then I think Bernie will seriously consider conceding.
You do know that, like, epistemologically her chances of being indicted remain non-zero after she gets the nomination or even after she's elected president. Your position is Schrodinger's Bernie. As long as we don't open the box to see if the Clinton cat ate the FBI poison, we don't know if her quantum candidacy is dead~!