Why does Metroid Mainline Games sale so sell low? And could it sale higher now?

[Wyrdness]

Dunban67 said:

Stefan.De.Machtige said:
At this point, Nintendo will have to reboot the series in some great way for just make the 2 millions range possible.

I m not so sure-  Existing Metroid fans are hungry so there would be a strong "by in" from existing fans for a mainline Metroid-   If it is a 3d Prime type game then IMO there will be alot of new fans wanting to experience what all the Metroid fans have been talking about- plus Samus is getting good exposure in Smash games-

Also look at Fire Emblem-  It was thought to ne dead in the West (by Nintendo) then went on to record sales with its newest iterations

Existing fans barely make up 1m, the only way for Metroid to consistently sell more than 2m is for a Fire Emblem style overhaul but then old fans will be moaning. New fans are even more of a minority as Metroid requires a very distinct taste and mentality from a player.