It could be one of their retirement release projects to wait on the back burner for now.
That's been my theory for a long time since they've let the relevancy of several live releases pass. Donington 2007 is well known to have been filmed and produced for a live album, and around the time of Dance of Death when Steve admitted to having some severe back problems due to the weight of his bass, he said that every tour was sacred and would see a live release.
If that philosophy is still the rule in the Maiden camp, I'd say we'll absolutely get Maiden England 2012/14. I can see why they'd wait until after retirement, since they'd just re-released Maiden England '88, which could confuse more casual buyers as to 'wait, didn't I just get this?'
I don't mind all the live albums, but I've long said that it's a golden opportunity of epic proportions that they've missed. If you already know you're making a live album of each tour, why would you put the same songs in each one (Trooper, RTTH, Hallowed, etc)? Put in unexpected material each time, and maybe rotate a few of the "must-play" songs, but populate MOST of the back catalog stuff with deeper, or at least less predictable material. That would make each live album, particularly for the hardcore fans a must-have, gotta-buy album, whereas now it's "eh, same old, same old, except maybe with a few new album tracks, so I'll pass on it."