I'm pretty sure that when Nicko decides to leave it's the end for Maiden, what I mean is that they probably already decided that they all end it together.
I'd like to see it go down that way. But I'm not so sure if the "cynical" side of them would prevail in a scenario where Nicko, freely and of his own will, says "guys, I can't do it anymore, I'm out, you do what you feel is right to do" and they continue, with the other 5 guys and someone you can't see anyway behind the kit.
They've been the best at many things, I hope they'll be the best also at retiring. All of them six together, this is the final album, this is the final tour, this is the final show, thank you and bye bye. No prolonged tours, no Bruce / Steve / H and some session players, no greatest hits tour after the goodbye tour etc.... I want them to go on until they can, and when they say it's over, that it's all really over.