I think some were sold to Denny's. The original owner of that chain owned the former New Orleans Jazz in the NBA.
Sambo's was a name crafted out of the names of the two founders. Naturally, it found itself associated with the "other" Sambo, and capitalized on it for years.
Until another literary character manifested herself in the form of all the wannabe Diana Moon Glampers.
I used to go to a "No Place Like Sam's" with housemates. I don't think it lasted all that long after the renaming.