Cantrians have a natural life span. I see a few situations:
1) They will live as long as the RP keeps them there. If they are active and RPing, killing them would be more harmful to the game.
2) There is not sufficient RP and the player effectively kills them (heart attack or starvation). So no problem.
3) They are killed for their lack of contribution (e.g. sleeping). So not really a problem.
4) They are killed in a CRB-fuelled killing spree. The problem here isn't the killing of the characters...
So I don't see a situation where killing old people will actively help RP and the game. The real issue is the sheer length of time things take to build. And I mean basic things (knives, hammers, clothes, resource collection) rather than motor vehicles. Most businesses fail in Cantr due to the sheer amount of work in setting up in comparison to the small number of chars to sell to.
My immediate preference would be to implement item quality, to add some value to experts (a thread which Echoman merged with old threads and promptly got no feedback at all

). Then we can consider standardising build times (irrelevant to skill), and hopefully encourage players to keep building and developing. We need to find a way for the mechanics to assist RP rather than eventually killing it through player frustration.
EDIT:
Joshuamonkey wrote:...not allowing older characters to do certain actions or to be weaker...
Limiting certain actions, fine. Making them weaker - hell no. Strength is already horribly unbalanced with certain chars being able to drag others singlehandedly.