I know, which added to the novelty of your post.
> The unsustainability is this: if U.S. labor costs $44/hr (or $30 even, to
> please Nathan), and Mexican labor costs $1/hr (or even $3/hr), at the very
> least, GM will run down its plants in the U.S. until they're worn out and
> hire no new U.S. workers. The UAW can strike to slow down the process, but
> unless they're willing to challenge managerial and stockholder power,
> they're not going to stop, much less reverse, it.
If GM can survive paying $44 or whatever, to be unsustainable somebody else has to be able to steal their chestnuts. Like Marx, you seem to exaggerate the competitiveness of markets. Simple expeerience suggests that the system is flexible in terms of its stability in the face of selective destruction of capital (e.g., bankruptcy). You lead me to believe you think likewise. But that's a different matter than the necessary supremacy of the fittest (in terms of cost reduction, in this case).
A variety of factors explain GM's ability to exist in the face of huge labor cost ratios relative to Mexico. Clearly there is erosion of labor standards in the U.S. which is trade-related.
My second point is that you paint this process as subject to binary disposition. We either stop it by challenging capitalism, or we suffer grievously and indefinitely.
If there are intermediate degrees of remedy, and if the political system is more open than you make out, then muddling through with social democracy may be the best available option.
This reminds me of the old saw, "no solution, no problem." It's like trying to solve 'the problem of death,' rather than focusing on how to make this life as fulfilling as possible.
MBS