Here in Germany meat alternatives/substitutes have definitely reached a level of popularity that goes beyond a fad.
The leading commercial producer of deli-meats has started producing vegetarian and vegan alternative products that now make up more than 60% of their annual revenue and they even dropped some of their original meat based products in favor of the plant-based alternatives.
It might not be the burger that's going to be replaced but sliced meats and other meat based products might be.