[yummyfajitas]

I don't claim that equilibrium can't change.

A speculative bubble is not an equilibrium. It will inflate and pop all on it's own accord. The housing bubble inflated and popped without any underlying changes in fundamental factors (e.g. population).

In contrast, a Nash Equilibrium based on signalling will inflate and remain until some fundamental factors change. Women will continue to wear high heels and people will continue getting unnecessary education until these activities stop being a means of obtaining status.