No, the longer the time is between a request and the actual event, the harder it is to anticipate how one feels and how one interacts with the world.
I think it's possible to have an informed consent when it's for a very short period of time, but the longer the time gets, the more you change. I think it would be very hard to have informed consent. I think this will become collaborative decision-making. I don't think it's as simple as just taking what somebody describes they might have wanted and what their suffering would be, then having everybody being able to act on it. I think it would be really complicated.