I'm not sure if Fort Max would be profitable. I've heard reports that a lot of the larger Encores like Metroflex and Omega Supreme have been shelf-warming - and Fortress Maximus would utterly dwarf them (both physically and financially).

As much as I would love to see an Encore Fort Max*+, considering how Metroflex and Omega Supreme are reportedly shelf-warming, I wouldn't blame Takara for not reissuing any more base/city-formers. If these reports are true, and I were in TakaraTOMY's position, I wouldn't reissue Fortress Maximus.

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* because you just know that Takara would reissue it with the Master Sword - and we know that they do still have the Master Sword mould since they used it for the God Fire Sword (albeit w/ retooled handle for God Fire Convoy)
+ and an e-Hobby Grand Maximus would be make me so happy that I'd need to change my undies