Frontman Dave Mustaine recently confirmed that Megadeth has moved on from Ellefson and ruled out the possibility of Ellefson returning to the band in the future.
Last month, Mustaine teased that the band had a "stellar" bassist lined up to replace Ellefson on the new album, though he admitted some uncertainty as to whether the bassist would be joining the band to tour on the record.
In another Cameo to a fan named Alex, Mustaine briefly showed the new member — although the musician was hiding behind a chair with so as to protect his identity until the official announcement can be made.
Ellefson was fired from Megadeth in May after sexually explicit images from video calls between him and a woman not his wife were leaked online.
While Megadeth initially backed Ellefson publicly, as the band waited for more facts to come out, police records show the band fired him within a few days of the leak.
Ellefson and his lawyer announced plan to press criminal charges and a civil case against the person who leaked the images.