My fundamental observation is that there are a lot of people who are not particularly suited for knowledge work, but are funneled/attracted to it because it's the only viable path to a reasonable effort:outcome lifestyle ratio. Therefore, my fundamental hope is that yes, I want there to be fewer knowledge workers. In place, I want AI that enables people of various competencies to succeed. I'd much rather see AI make my carpenter friend, who made an awesome desk for me, be empowered to compete as a solo/SMB against big retailers: perhaps by automating his marketing, streamlining his ops, participating in design, and so on.
Uncharitably, is your complaint "a lot of people will have to labor with their bodies and minds differently, and it's easier to sit down"? I'd ask you: is butt flattening really all that "must preserve knowledge work" has to recommend it? Because your comment doesn't hinge on anything else except that construction work is back breaking. Well, construction is a diverse field, and it can benefit from the inclusion of intelligent and motivated people, just like many others.