I had thought similar for some years / decades.. the past few years my views on older people having sex / not / alot etc have changed quite a bit.

Certainly there are some old couples that stay together without good sex for different reasons, religios beliefs and such...

But if you are an intimate couple - that includes sex. If you are not having sex you are just roomates / friends - and there is nothing wrong with that.

I know a few different people in thier 70's right now having really great sex because they have found new partners, and because it's great they are having a lot of it.

So it could be less important if both people's only goals are stability or other goals - however we are seeing from reports in retirement communities and nursing homes that whether it is the loss of partner through death or divorce or just ageing single into a new community of options - that people are indeed searching for sexual compatibility as they age - often times with many more partners later in life than mid-life.

The most parameters are: who you are as a person and all that comes with that.

Saying that this matters less when that, or you'll loose interest in sex as you grow older simply won't fit for a lot of people. But for a lot maybe it will.

But since all of this is such a inherently personal thing, its opinion around the world will be as divided as our own butts.