If that starts happening (farming out S version to other studios) it'll spell a quick death for a console SKU that's already struggling to find a footing.if you have enough money you can work basically on two version of the game
That said I'm wondering if MS would even allow it - those parity contract-terms aren't just for competing platforms.
Anyway - none of these are a real issue until legacy SKUs are out of the picture, right now it's all 'upgraded current gen' for multiplatform releases, which benefits Series S above all for scaling.