If RDR2 is anywhere near the environmental complexity of GTAV, there's no way that Scorpio will run it at native 4k without significant compromise in other areas of visual fidelity.
As far as third-party multiplat support goes, history has shown us that the best hardware does not always mean the best version of the game. Especially when you're talking about pushing 4k on hardware that is barely capable of achieving that with a consistent framerate. Not to mention the fact that platform specific optimization with third-party multiplats doesn't happen as well as it should anymore, meaning devs are wasting power just because it's there to waste in some cases.
Also, you're fooling yourself if you think games released 5 years from now will run at native 4k on this thing without having to turn other settings way down or running at sub 30 fps. The demand for high visual fidelity will continue to get higher and devs will continue to push the envelope.
I would say, as with all things technology, that you all should temper your expectations.