I'd say the Witcher Trailer and the Cyberpunk trailer are a bit different - the Witcher trailer was basically one of those 'in engine graphics' ones, where they're not really showing you actual gameplay, rather a sort of 'gameplay trailer' which was probably all pre-rendered whereas with cyberpunk we saw someone actually playing it a good chunk of it.
I can imagine they might downgrade it a bit, but I doubt it'll be drastic - it'll probably just be that they have to cut back on some of the lighting/effects so that consoles can handle it, but I doubt it'll be much.
For the record though, I honestly don't think there was much of a downgrade with the Witcher 3 - they apparently took out:
Level of horizon detail (essentially the draw distance had to be completely tuned down to tax the consoles less)
Volume based translucency
Ambient occlusion and foliage density / tree count
Flexible water simulation / tessellation we resorted to a (script texture effect similar to most games than physical based simulation)
Ground/building tessellation
Forward lit soft particles (this is the fire, smoke, fog that you would encounter while going through thick terrain into open space)
Real-time reflections in the water are completely off and replaced with a cheaper render solution estimator (this is a primary reason blood splatter was also removed from water)
All due to having to downgrade it for consoles and because a lot of the stuff that they used was Nvidia only tech with no analogue. Whilst the effects look worse (and the water does) it isn't like it's a huge step down like Watchdogs etc.
Also, after the flak that game devs have been taking recently for doing the bait and switch with trailers I really doubt they'd do that. CDPR seem to be very on the ball in terms of not making the usual industry mistakes, and they certainly aren't rushing into anything.