The bassist joined Axl Rose's current version of Guns N' Roses during a concert in London last year, but it proved to be only a one-off reunion.
McKagan said that a tour featuring Rose, guitarists Slash and Izzy Stradlin and drummer Steven Adler hasn't been discussed, but he won't rule out the possibility of a reunion.
"Of course there's a chance. I don't know how real that chance is," McKagan told The AP.
"It's [just] not something I ever write about or talk at home about or with any of those principal people about, ever."
Adler was the first of the Appetite for Destruction lineup to leave Guns N' Roses after being fired in 1991, with Stradlin, Slash and McKagan following suit in the next several years.
Slash and McKagan later regrouped in Velvet Revolver and also recently performed a special concert to raise money for recovering drug addicts.
Rose's current incarnation of Guns N' Roses will kick off their first North American tour in five years on October 28 in Orlando, Florida.
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Watch Guns N' Roses perform 'Live and Let Die' below: