Lv426? That would mean the planet would have to be nuked / atmosphere destroyed before the end of the movie in order to have a scorched cold planet with boney looking protrusions in time for Alien, and an unbreathable atmosphere that requires atmosphere reprocessing towers in Aliens.
I suppose you could go back and spend money and time re-terraforming a planet, although it would make more sense to keep exploring other worlds.
If it is LV426, I really hope what scorched the planet and maybe eradicated aliens/spores was a natural mass extinction event like a comet or something more science driven than just the covenant survivors taking off at the enr of the movie and nuking the planet from orbit.
In fact, even if its not lv426, that is how I would like the movie to end. A natural mass extinction event wipes out everything, maybe pompeii style. The camera rapidly cycles through the planet experiencing an ice-age. Then things start to thaw. Last shot is that of some strange new egg/spore thing that somehow, unlike the dinosaurs managed to survive even a mass extinction event. The End.