He has done so very much better in this race than what the media would have us believe. If you look at the actual delegate count (have to dig deep for that, because they're still placing supers w hilary), it is much closer than you might think. After today, it will be even closer.
No reason at all for him to drop anything. Whites are backing him, and many of them will not back Hillary. So Bernie should stay in it to keep the pressure up. It's not over.