I suspect that your question is a bit 'loaded'. Our sexuality is affected by aging, both negatively and positively. Aging does not mean that there has to be a loss of sexual function, frequency, or enjoyment. If you stay healthy, and if you need a medication for ED, your sex life should continue as it has in the past.
But many people encounter sexual desire issues and functioning issues that are not at all about the physical, but about the emotional and about intimacy (in the larger sense). These issues are predictable in long term relationships, and can be overcome with the right knowledge and motivation.
On the other hand, there is an added salience and intensity that can be achieved during the fifth, sixth, and even seventh and eighth decades that cannot even be approached in your younger years. Sex from fifty on can become far more than just pleasant physical release; it can become sublimely spiritual and deeply, deeply intimate.