Alas, but no. The reason I don't expect my current decisions to be preserved into, say, the next year, is because I expect something crucial about my situation to change during the intervening period. For instance, take this example:

Don't want to move away from your parents today? well then you must never want to.

Sorry; that's just plain wrong. If I don't want to move away from my parents today, that's due to a number of reasons: I might be underage, still economically reliant upon them, still need to attend school, etc. On the other hand, I anticipate with high probability that at some point the above statements will no longer be true; there will come a point when I am no longer underage, no longer dependent, and ready to go to a fancy out-of-state college, say. The point is, I expect my decision to change because I expect the surrounding circumstances to change. If for some reason I was persuaded that I would forever remain an economically dependent minor, then perhaps I would want to stay with my parents forever.

Note that this is not the situation our supposed deathists find themselves in. They are not expecting some future change in their circumstances that would render death suddenly a thing that they want. They don't want to die today because they are (for example) living comfortably in a retirement home, interacting with their children and grandchildren. There is no reason to expect those conditions to change anytime soon barring death, and in particular, there is no reason to expect those conditions to change in such a manner as to make death preferable to life.

And for good reason: try to imagine a situation in which you are happily living your life one day, and suddenly want to die the next. All right, I bet that was pretty easy. Maybe you were kidnapped during the night and subjected to extremely painful torture that you were told would last for 50 years. Maybe you developed some mental disorder causing you to become rampantly suicidal. Or maybe it's just that you received a notice of foreclosure; that's been known to drive people to suicide, after all. Now let me add one more caveat. It has to be something you were expecting in advance--not necessarily that you knew it was going to happen on that day, but you knew it was going to happen someday.

Suddenly not so easy, is it? Death is one of those things for which your preferences should never change outside of some extreme circumstances that are minimally probable at best. If you don't want to die today, there will never come a day when you do want to die ("Oh, man, it's Tuesday! Wouldn't this be just a fantastic day to commit suicide!") barring the possibility of black swans. And that makes "wanting to die" a very different beast than "wanting to move out from my parents' house" indeed.

My assertion is that there's a difference between wanting to die and being apathetic about having death sneak up on you, and that most old people are actually in the latter category. I'm not comfortable calling these people "deathist", preferring instead to reserve the term for those who would oppose the idea that death should be optional.

I hold that the person who merely wouldn't mind not waking up tomorrow is usually just as content to keep living for one more day, and would likely be at least as content to wake up in a younger body.

The guy living in his mom's basement who says he would like to leave is less ambivalent. He would much rather wake up in a place of his own, provided he didn't have to make the continuous effort normally needed to enable this.

If dying took as much effort as getting and holding a job, I doubt it would be so popular.