"the point we make in the book is that few employees expect or want lifetime employment at a single company;"

Expect? Of course not, anymore; you'd be a fool to expect that.

Want? Well, more complicated: if it's a matter of wanting lifetime employment in the presently existing field of options, as employment and firms are presently constituted (and as firms presently look at employees), maybe not. If it's a matter of wanting to be working in the kind of regime in which lifetime employment really was more common, the answer might change.

Your response to 3 is a non sequitur. And employment as a condition is certainly not a voluntary matter: think of what that would mean! (Hint: it would mean that anyone who wanted to could quit their job and not seek employment elsewhere and things would be fine. We don't live in that world.)