Tezuka and even Miyamoto really don't have much experience actually running a business.
Yamauchi didn't hire Iwata because he was a game designer. Yamauchi had hundreds of those.
Iwata was hired because he was president of HAL for several years and successfully restructured them from a company in large debt to repaying that debt in about six years or so. He had management experience in other words on the business side.
I don't know where Nintendo goes from here. I think for the next year or so Miyamoto and Takeda will operate as joint presidents until they can find someone suitable to accept the role.
Maybe Satoru Shibata from NOE makes some sense.