I think they have mostly moved to handhelds. Low development costs, large user base, and sufficient power for the core elements of the games makes them an ideal platform. I guess it is possible that I am wrong and they are fading, the same thing happened to a large number of old multi-sequel PC RPG franchises in the US-- see Zork, Ultima, Wizardry, and Bard's Tale. The thing is that I have no clue why this would be happening in Japan so I prefer the idea they are moving to handhelds as they seem to be there and selling well.
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