I disagree, not with your premise, but with your conclusion. Witcher is one of my top 5 games of all time, but BOTW is probably pretty close. I agree that Witcher offers a more fulfilling experience, particularly narratively, but I don't believe that the Witcher's strengths are as easily copied as BOTW's. In particular, I would argue that if there is any deficit of talent in the video game industry as presently constructed it is in writing and narrative design. Witcher is the clear exception to that and presents some of the best writing ever seen in games. Other production houses are, in my opinion, simply not set up to be able to match that success.
Look at Assassin's Creed Origins, a game I really like (so far). Origins is the clearest example we have of the Witcher's influence. You can see it in every moment of gameplay. Equipment, questlines, RPG skill trees, etc. And yet... its simply not as good. There is a shallowness to its quests, to its overall plot, to its pacing that is nowhere present in Witcher. The Ubisoft developers, as many of them as there are, were not hired with an emphasis on the narrative design that the Witcher brings to the table.
On the other hand, BOTW is brilliant, but I can see many more of its ideas being able to be copied by other developers. Fire as element. Weather effects. Climb Everywhere. Opaque quest direction (the real jewel in BOTW's crown, in my opinion). These things exist in physics engines and world design that is the primary strength of the current industry. Because of that, I think BOTW's follow-on effects will be more keenly felt than Witcher's as folks like Ubisoft (or more importantly their investors) realize that copying Witcher is actually really difficult.
