What would happen to heavy metal? Well, let's just say... is Mozart dead? Yes. Is his music dead? No. People still listen him. Heavy metal will continue to live, regardless of new bands appearing or not.
Ever listened to Sturm und Drang cover of Fear of the Dark? Damn, I realised they changed nothing only after 5th listening. Only Iron Maiden can perform Maiden songs.
Montsigur
Paschendale
Face in the Sand
About album being strange, that is just proof how good IM are... they can get out of standard way without losing any quality.
They are old school but that makes them better, not worse... and they're certainly cool. Of all existing metal types, (traditional) heavy metal is best.
Friend brought me Best of the Beast album, I liked it and downloaded first individual songs then whole albums (now I have Number of the Beast, Peace of Mind, Killers, and Powerslave too).