If I knew their wishes - of course. I'm not saying it would be easy, or anything of the sort, but if it was their wishes, then I would take comfort in knowing that.
I know the wishes of my mother, and even after caring for people who were recovering from injuries that at one point had been deemed "unsurvivable" and were going to be 'turned off" - and are then able to return home with just a small amount of lost function - I still would honour my mother's wishes. We've even discussed it - my step-father and I know what she wants, as does my younger sister. HOWEVER, I do hope it's never something we have to do.