How long does income from a website lasts?

Is there a deadend to income from a website?

It seems possible that trends do come and go. So guys, any example of a type of great website business with constant profits? do you forsee adsense or affiliate models lasting longer in general income producing terms? idea is to get constant more durable income vs short term spikes in profit that do not last.

Your personal website will not die as long as it is a great niche, and you keep on maintaining it. You see this problem in a bunch of weight loss related niches. A famous 'TV' doctor recommends a certain product, sales boost. But then the next big thing comes along, or the 'miracle' weight loss method is proved not to work; and the niche dies.

You can build small websites for current trends, then sell high. You never have to think about maintaining the website because it is not yours anymore.