Unless Sony wants to write a big check(they wont) it would definitley be mutiplatform.
But what if Sony Co-Develops it? I mean, they could have some of Studio Japan and Santa Monica (they are fimilar with working with JP developers; reportedly sent over some team members to help out with TLG), so them helping out with this would justify exclusivity (even then, it could be a timed exclusive for half a year).
Either way, if this really does happen, that will be amazing .