Some of these farms are truly impressive. Although balancing the health of the fjords is hard. People seem to prefer "wild" salmon but just like we don't eat "wild" cow anymore, I imagine in 30+ years it will be the norm. Hopefully we can shift to that norm in an environmentally friendly way.
We don’t eat wild cows anymore because aurochs went extinct in the last few hundred years.
People still eat junglefowl (ancestor of chickens) and wild boar (pig), but in the developed world domesticated animals are usually both cheaper and tastier.