I imagine that you would need to buy the Sony version, unless SE worked out a good contract, as I doubt they'll see it as just a patch especially since it is being sold as a separate piece. Also SE may just have an agreement to pay per content update (regardless of delivery)... perhaps they wouldn't care how it is sold then. It isn't known, but I have faith Sony is getting something and if I had to make a plan without having more information I'd work it around Sony.
Hopefully SE can do something that isn't complicated or annoying as buying the expansion twice.