We inherited blackcurrants, gooseberries, raspberries and strawberries when we moved into our current property ten years ago.
The blackcurrants and gooseberries still seem to be giving a healthy yield and it looks like they'll go on for nearly for ever. The strawberries and raspberries started to fade about 5 years ago and we have removed them.
What's the recommended lifespan for strawberries and raspberries?
Raspberries can grow productively longer, to around 10 years, as long as you rejuvenate/prune the fruiting canes properly. Strawberries, like JonH said, get around 3 productive years of fruit-bearing before they succumb to disease and age, giving it a lifespan of 4 years or so.
There isn't a set timeframe, but for strawberries and raspberries, you can usually get a good 3 seasons out of these fruits before it is time to replace. So I usually stick with 3-4 years, and you will definately notice it as the yield of fruit decreases as time goes on.
