My “600 words” all apply to them, but Pascal’s wager is especially favorable to the old.
Consider: (1) As a preliminary matter, they have less excuse to avoid making their choice. (2) The “next life” considerations are stronger for them, since the next life is closer. (3) The “this life” considerations — and this is the strongest point — are much more weighted in Pascal’s favor for the old: (a) the worldly pleasures they can gain by not believing are less (sex, drugs, rock and roll) and will not be available for as long; and (b) the comforts of faith are greater.
To elaborate: Each “quadrant” in Pascal’s wager (you believe and He exists; you believe and he doesn’t exist; you don’t believe and He exists; and you don’t believe and He doesn’t exist) has “next life” and “this life” considerations. So there is infinite payoff in the first quadrant for the “next life”; that’s the same for young and old, but the “this life” payoff is greater here for the old than the young if, say, God is more likely to provide comfort to them in their afflictions and as the prospect of death draws nigh. In the second quadrant, the old may take some comfort in their belief even if they are wrong, and are less likely to give up some pleasure. In the third and fourth quadrants, conversely, the old give up comfort in this life by not believing. The comfort, by the way, is both psychological and physical — that is, the positive thought may actually improve your physical well-being as well as your peace of mind.
I would also note that carrying the evangelical message to the old has some urgency, again precisely because they will not be with us much longer.