Their plan has been album, album tour, album tour DVD, theme tour, theme tour DVD, lather, rinse, repeat. And I'm pretty sure they want to do a theme tour for each era up to Bruce's return, which means at least two more theme tours, which by my reckoning means two more album cycles as well.
That'd make them about as old as bands like Priest by the time they get there, which I don't think is out of the realms of possibilty.
I guess we'll see.
29/10 Saint Vitus
13/11 Judas Priest