This is likely too spirited of a discussion for this section.
I'm of the opinion that it should be left to individuals. If they haven't made that decision, it should be up to their families.
Medical intervention is just that - intervention. I probably go a lot further than most people here in what I consider intervention, as my beliefs lead me to believe people have the right to refuse all intervention, if they wish, for themselves and their children. However, as you only asked about life support, I'll stick with that.
If one wants to intervene, is it wrong? I don't believe it is, as we were given brains to use and science has used it to do some wonderful things. Can it go too far? Definitely. If one wants to take it and make a law of it, that is going too far. One can't take a natural process, intervene with science, then make it wrong if a human being or their family refuse to allow that intervention. It should be a choice.
Since it does deal with life, it can get sticky. Since it was brought up, I don't believe the case of Schindler-Schiavo fits into this scenario because of the surrounding circumstances and evidence I believe shows she wasn't in a persistent vegetative state. After quite a bit of research into her case, I concluded that it was mishandled from the beginning to the very end.
Not only is there this type of support, I've watched in sorrow and held people's hands as other types of "support" were given in non-DNR situations where it was simply their time and known, no arguments about it, no surprise to anyone, support that only prolonged the natural death process. However, some things are "required" by law and still done by sticklers for those laws, like giving IV fluids and nutrition once the person has stopped eating and drinking. Just those few extra days brought about some very unnecessary times for what should have been a more peaceful exit for them without...well, don't want to say what happens when you go against the natural process in some cases, it isn't pretty, and it's wrong to have to disturb them in their last days to swab and wipe them because of the stupid "helpful" laws that use no common sense and leave no room for logic.
So that's life support IMO too, because it keeps them alive and doesn't let them die at their time.