Honestly I don't see the fact that this is a double album as any indication that we will be getting a drastic departure from what Maiden have been doing for the past 20 years or so. It seems like they didn't set out to make a double album, in fact without the 18 minute epic it probably would've fit on one disc. So I doubt there was a conversation like "Ok since we are doing a double album, should we try anything different?". So given the way they write now, I think an instrumental would only happen if they set out to write one and I don't think they're interested in that.