Iwata can stay but NOA should be handed over to real Western-centric management.
Miyamoto should be removed from head of software division at EAD though. EAD's software focus has become way too narrow.
Keep Miyamoto around sure, let him personally work on whatever game(s) he wants and give him whatever budget/time he wants for those games (and he's obviously earned that), but he shouldn't be the one making calls on the overall software direction of the company anymore (and anyone else who was responsible for Nintendo's library/software planning of the last 2 years should also be demoted).
I would promote Koizumi. He's younger and seems more in touch.