It would make more business sense for Nintendo to hire all the "old" Rare staff, form a new studio, and offer them complete creative freedom. They wouldn't have the IP's, but they'd have the talent in order to create new ones. Considering how disillusioned the staff (or ex-staff) seem to be, I'm sure most of them would jump at the chance.
Hell, it makes sense, as Nintendo sold their stake in Rare due to a combination of the Gamecube not performing too well, and Rare taking so long with their releases. That $250 million or however much it was, was worth more to them at the time. But Nintendo are doing so well right now, they could afford to let "New Rare" have long gaps between releases. Not only that, but despite the fact that Nintendo are still putting out plenty of "hardcore" games, they're still putting a lot of their time and effort into catering to the casual audiences. Having a second-party dedicated exclusively to hardcore games would be a good thing.