Scorpio is obviously capable enough for 4k 60fps, just as Xbox One Is capable of 900p 60fps. We dont see it very often but it's achievable. 4k, 30fps shouldnt be a rarity if Devs priorities resolution over graphical enhancements
There will obviously be a notable resolution jump and potential for better performance than any competing console, so I dont really care about native 4k. If you get given something above 1080p then you're making good use of your 4k tv. I don't see the value of Scorpio being judged by how frequently it natively hits 4k on the dot. I mean Ms could make a 8Tf system and still nothing is certain for as long as developers have freedom.