Obviously this would be the best possible scenario for Donald Trump and the Republicans.
Bernie Sanders has been treated terribly by the Democrats—both with delegates & otherwise. He should show them, and run as an Independent!— Donald J. Trump (@realDonaldTrump) April 26, 2016
IF Sanders took Trump's advice, and to be fair there is no indication that he would, it might well hurt the Democrats enough for Trump to win the election.
Of course there is no real good reason for Sanders to go this route as he would have absolutely NO chance of winning, and it would literally destroy his credibility and reputation as a progressive. (After all any politician who handed Donald Trump the keys to the White House could hardly call themselves a liberal.)
So no I don't think that Sanders would go this route despite the Donald's urging.
However I also hope that Sanders does not actually take this thing all the way to the convention, because every penny that Hillary spends in this primary is one more penny she cannot spend fighting against Donald Trump for the future of this country.