I've always wondered if the average human lifespan is somehow implicitly factored into interest rates. If people lived to 1000+ years old, a small investment made early in life could potentially balloon into incredible wealth given even relatively conservative investments. Obviously political and financial stability could have huge impacts too. I have to imagine multi-century-long held accounts would have an impact
I think the markets will regulate themself as they always do. If (actually, in such scenario it's best to say when) the accounts held for a vastly longer amount of time start to spread, there would be at most an initial impact, but then the markets will stabilize automatically and nothing will by disrupted unrepairably. What now we call "short term investments" will become very very short terms, and so on. There's nothing that will be distructed on this side in my opinion.
What could lead to problems (that is: a not changing social and political situation) would be the adaption of political mechanism for the longer lifespans. For example, now politicians have mandate that last from 3 to 5 years, then there are elections (talking about not totalitary states). Putting this in prospective, with humans having a 1000+ years lifespan, politicians mandate would grow to 50+ years. That's bad, and in my opinion will only lead to deadlocks.
Imagine a nation guided for 50+ years by the same persons. They will start demanding always more power, leading to mostly only totalitary scenarios. Everything will fall apart.
Instead, keeping the actual model could lead to even more variety (that's not the right word in this case, my apologize for it) than what we have now, and there's a reasonable chance that humanity will benefit from this.
Of course, the one described is just one of the worst case scenarios (altought not the worst at all), maybe our brain will change drastically and we will become a complete different thing.
That seems logical. I think the average lifespan is factored into nearly all facets of human civilization, implicitly and explicitly. Come to think of it, I probably take my expected lifespan into account when making all kinds of decisions, both consciously and unconsciously.
