One of my pet peeves of AI is that the term is just plain wrong, even in literature ( Artificial Intelligence a modern Approach - usually considered a good introduction to A.I.), they somehow lament the term and propose something like computational rationality instead. ( try marketing that though).
One issue is that from the other side of the argument ( Human Intelligence ), in the fields of cognitive science, logic, psychology and neuroscience, there is not a hard,simple or unified definition of intelligence, yet most of us have a definition we more or less agree with in our minds and usually transplant the term to A.I.
So in this case, the threat would come from an A.I. that not only designs the product in the nuts and bolts kind of way, but also comes up by itself with all the other things that a designed product is : A solution to a human need embedded in the current culture, with fine aesthetics, environmental considerations and on and on.
What most of the current and past ( A.I. started around the 1940's) A.I.s do and do increasingly well, is efficiently find solutions by borrowing know-how from the programming,biology and scientific world, but, and this is the crux, it is generally to a very specific problem that is usually known beforehand and it is strictly defined: a weight bearing strut system, is the picture a cat, can I drive or vacuum in this area, how to cut some shapes efficiently etc,etc.
So it seems we are living in a period where A.I.s will raise the bar by providing solutions, insights and variations to design while being guided by designers in a partnership.
The loss of jobs is harder to weight, technological unemployment has been a constant in human society, for the last centuries it has mainly been driven by machines that replace human manual labour, more recently it has been data manipulation,and even more recently services, but long term global unemployment has remained relatively stable (~6-8% ) due mainly to our ability as society to self regulate.
For instance, the other day I was designing the guts of a small electronic thing, it took me about a week and basically it involved providing structural support to a few electronic boards & components & making sure it would fit on the outer enclosure while minimizing material costs, let's say a studio does this at a greater scale with a team of 5 designers, a new software tool appears in the market and provides this same functionality, what happens next?
Well you could fire the 5 designers, or you could realize that now you can crank designs 5 times faster with your existing team, what's more, other studios will be doing the same, so maybe hire an additional designer ? It's a simplistic example, but I believe it shows how the markets could adapt to this type of disruption.