I think whatever the situation, it's expressly covered in the contract.
It could be anything from 'All SF5 assets are owned by Sony and can't be used without express permission.' to 'The initial iteration of SFV will only appear on the PS4, aside from PC platforms, future iterations will be negotiated as and when with asset royalties received in perpetuity'.
It really could be anything, and yes, the existence, and exclusivity of future iterations might be open to various elements of the contract, sales performance, metacritic score, XBO market share, etc. We'll never know those details.
But in any of those possible situations, they'd be covered in the contract, so the possibility will have already been accounted for, so it would be possible to be transparent about those things. I don't expect them to, I never did, of course, but I think the exclusivity is far from 'clarified'.
If the series wasn't so infamous for these iterations, it wouldn't be so cloudy. TitanFall for example, someone says TitanFall will never come to PS4, I would be very confident a TitanFall GotY Edition wouldn't come to PS4.