Since AC/DC formed in 1973, guitarist Malcolm Young, along with his brother Angus, has been rocking the planet basically nonstop. After over 40 years with the iconic rock band, Malcolm Young has been sidelined with serious health issues. Malcolm's future with AC/DC is still in question, but Jesse Fink, author of the new book 'The Youngs: The Brothers Who Built AC/DC,' says he's "not expecting to see Malcolm return."

The Young family and AC/DC have kept the details of Malcolm's illness private, though it's been rumored that the rock legend had suffered a stroke, could be dealing with Alzheimer's, dementia or possibly cancer. A source has also claimed that Malcolm is having trouble recognizing familiar faces.

Boston radio station WZLX spoke with AC/DC biographer Jesse Fink about Malcolm Young, uncovering what could be the most detailed explanation of Young's future to date. “I’m not expecting to see Malcolm return," says Fink. “I think the important thing is we all let Mal be and hope he can recover. But I think we should all expect that Stevie Young (Malcolm's nephew) is in the band now.”

In addition Fink tells Ultimate Classic Rock, “As far as I’m concerned, his illness is a private matter. However, fans seem to think his illness is just going to quickly go away and he’s going to be there on stage when they announce their tour. If what I have heard from numerous sources is true, then I expect Stevie Young will be touring with the band and not Malcolm. That’s not a seditious viewpoint. It’s realistic.”

Though Fink's insight is somber news, the biographer speaks well of the band's upcoming album, their first ever without Malcolm. “I’m hearing on very reliable authority the new album is up there with [2009′s] ‘Black Ice‘ or even better,” Fink reveals. “So Stevie must be a good replacement for Mal.”

AC/DC are hoping to release their latest album in 2014. Stay tuned for more on AC/DC and the band's newest offering as news breaks.