The styles are soooooo different, I can’t see what would develop.
When I read the question, I considered that Bowie and Dylan both changed their names (David Jones and Robert Zimmerman), but Zappa was Frank’s real name.
Zappa satirizes Dylan in the song “Flakes.” He never mentioned Bowie specifically, but he didn’t care for glitter. In fact, a lot of Zappa’s satire is directed toward rock stardom, something I think he never wanted for himself. He was first and foremost a composer and musician.
All three have disparate styles. I can’t see them collaborating on anything.
I just won a little bet with myself that the first response would say “awesome.”
I couldn’t see any one of the three submerging his personality, his style, or his star status in a collaboration. But I think the battles would have been awesome to watch.
I think Bowie and Dylan would be fine collaborating together on a project but teaming up with either let alone both would have bored Zappa to tears and never ever happen. As @IchtheosaurusRex so astutely points out Zappa satirized most of the cultural icons of his time including Dylan….
__“Wanna buy some mandies, bob?“_ ”‘n’ they didn’t do nothin’” “But they charged me double for sunday”