Eubanks, who's been with Leno for 17 years, will still lead the band when Tonight returns on March 1, but his departure is likely within the first few months after that date.
Eubanks is said to be interested in returning to touring and working out a flexible schedule with The Tonight Show.
Melendez, meanwhile, was the Tonight Show announcer before becoming a writer on Leno's primetime show. He will continue in the latter capacity at the new Tonight while Leno and exec producer Debbie Vickers decide whether to use a generic announcer or hire a new personality for the new show.
In related news, Ross "the Intern" Mathews will be back.