Microsoft has already stated that the Xbox Series S will be using the Xbox One S variant of games, not the enhanced Xbox One X variant, that includes the Backwards compatible titles.
I think it was an odd decision since Series S is at least on par with X1X, and considering ram and CPU it is much better. But well they must have their reasoning and perhaps fanbase reaction may make they reconsider it.
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."