Originally Posted by
Captain Capstan
As the aircraft climbs the cabin climbs to maintain the differential pressure so the cabin will never burst.
Eventually you could get to an altitude where - at that constant differential pressure - the cabin altitude got too high (10k) and the masks drop - which would obviously be bad.
People tend to assume that the stated cabin altitude (8k for most airliners, 5 or 6k for some new ones such as the A350 and 787) is used all the time at cruise - in reality those numbers are maximums and if you do a low altitude cruise, the cabin altitude will generally be lower than that.