Other long gaps between projects from major artists:
Roger Waters - thirteen years (1992-2005)
Kate Bush - twelve years (1993-2005)
Peter Green - looks like thirteen years (1984-1997), though I could be missing something
Mike Love/Bruce Johnston - eleven years (2001-2012), Al Jardine - fourteen years (1996 - 2010). Obviously getting into debatable territory here about who's a "major artist".
Stretching the definition of "major artist" a lot, I'll throw in Vashti Bunyan (35 years) and Linda Perhacs (44).
That's not to mention people who basically left the industry like Syd Barrett or Richard Hell.