I dont know man. Zelda does this all the time. It's really not a big deal. Granted most of the drops are when you are using ultrahand, and walking around towns, and its fairly smooth in combat but starfields few combat sections looked very smooth.
The demo was native 4k and maintained 30 fps. I have no doubt that they will be able to get at least 30 fps working very smoothly. I think even 60 fps should be a possibility though Bethesda is one of the few AAA studios that utilizes the CPU to its fullest so they might just leave it unlocked.
I am not really worried about starfield. At least not on the xsx. The demo looked stunning (for a bethesda game) and ran fairly smooth with only one area dropping frames.
And honestly, this looks better than most next gen only games released so far despite being a bethesda game who arent really known for pushing visual fidelity. It really surprised me. The only thing that can fuck this game is if Bethesda rushes it out the door. They need to realize that games now take 1 year of QA testing after being complete. Thats exactly what Nintendo and SE did with Zelda and FF16 respectively. They finished the game last year but delayed it by a full year just to make sure it didnt break. I think Phil should be celebrated for delaying it instead of getting shit over it because then he just might rush it out to avoid a backlash over a delay.