All speculation my friends.
In a recent interview, Bruce did say that the band would cease all touring activities in around 5 years time, but continue recording and releasing material. (edit:Bruce has now said that this information is false according to a report on Blabbermouth)
When I met Nicko he told me about the 7x70 project (w/Dan Spitz) and said that their album would be released after the DoD tour had finished, and he would be heading out on a tour to support the album.
After this, he said he was confident that Maiden would then reconvene to start work on the next Maiden album. In my eyes, that takes us to around 2005/2006 - the tour would be likely to consist of festivals only, as of course the current tour is the final 'arena/stadium' tour.
It may also be advisable to note that in an interview back in 1993 (before Bruce quit), Dave Murray said that he thought Maiden would go on for about 5 more years, before packing it all in. Of course we all know that isnt the case.
Hell, when the Sun (UK Paper) ran a story when Bruce left, the headline read "Maiden to split as Bruce goes solo", and had all manner of quotes from the band saying that the band as finished. This as well, was trollop.
My advice? Enjoy em while you can. And when they do finally call it a day, we will all have a fantastic set of memories, albums and friends that the band made possible. Dont worry yourselves about doomsday. We can deal with it when it hapens.
Until then, UP THE IRONS!!