Just because someone is on oxygen doesn't mean that they are going to die soon--they could have years left to live. Had to provide an oxygen tank the other day for a kid who's had to use a filtration system for a couple of years. Putting all of those people in a hospital would not only be economically unfeasible, it would be pretty degrading and depressing for them.
However, I think it is safe to say that someone dependant on such a system should understand that they are at a much higher risk of death than people who aren't. Because, without technology, they likely wouldn't be alive.
