I suppose Series X assets would be on disc already. That's exactly how Xbox One/One X is being handled right now. Some games can have additional One X assets and if you install the game on One S or Xbox One it picks lower definition assets and if you install it on One X, it picks higher definition assets. The executable file itself is universal. The same would apply for Series X. Just one more tier of assets is gonna be added. That's what that "Smart Delivery" thing is about. And that's what makes it different from plain free upgrade like on Playstation consoles. If you buy a PS4 game on disc and want to move to PS5 later, you will have to either install PS4 B/C version from disc or redownload the whole PS5 version of the game through internet. The disc won't have a PS5 version of the game in any capacity. Also, it is still a question what happens if you buy PS5 version of the game on disc and try to put it into PS5? Will Sony allow free "downgrade"? Who knows.
That is what I was expecting, but from Shikamaru post you would have to download the specific XSX assets.
On PS5 I think we didn't get any formal confirmation on how the crossgen will work, if it will be single disc for both system similar to how you explained, if it will be just BC or if you buy PS4 disc it download the assets for PS5 version but if you buy the PS5 disc you can't put it on PS4. I know that on PS3 to PS4 for digital the crossgen offerings were just you could download the PS3 or PS4 version depending on where you were downloading but for disc I don't remember it being available at all.
duduspace11 "Well, since we are estimating costs, Pokemon Red/Blue did cost Nintendo about $50m to make back in 1996"
Mr Puggsly: "Hehe, I said good profit. You said big profit. Frankly, not losing money is what I meant by good. Don't get hung up on semantics"
Azzanation: "PS5 wouldn't sold out at launch without scalpers."