At his age, this seems like a very savvy move. Leave the family with a huge bucket of money, and no worries about how to "honor his legacy" and be the source of all ire and vitriol from his "real fanz" who hate the family for "cashing in on his integrity." Now he sold the whole kit and caboodle, and absolved his family of a lifetime of being pilloried by the press and fans alike. Good move, man.
If he was forced to do it by someone else (like Stan Lee was), then they are cutting their own throat. Bob Dylan's catalog is a fucking GOLD MINE of opportunity for someone to make a trillion dollars of selling 60 years of iconic lines, riffs, and songs for advertising, promotions, movies, etc. His "business manager" could easily get Bob to hand over assignment rights and make a billion dollars on that in the next year alone. This is DEFINITELY a Bob move: sell everything for a big lump sum, leave the cash to the family, and also - poetically - do the big "sellout" on his own terms. It would happen eventually after his death anyway... this way he gets to control it, and do it on unequivocally on HIS terms. That's some sweet poetry for someone who has juked the system his entire life.