> If you don't want your employability to dry up once rockstar ninjas become commonplace enough that the demand bubble for them pops,
This is the crux of your argument, and it's debatable whether this will ever happen. My feeling is that rockstars will always be rare. I don't think this is a function of supply and demand but rather just human nature.
I personally could be a rockstar if I wanted to. I bet a lot of us could. I just don't care to organize my entire life around my work. It's not that I don't know how to do it, there's no magic trick about it, it's not some rarefied thing that only one in a million can figure out.
I just want to focus on other things, not vomit code at feverish pace all day long. I don't think anyone but the most driven among us ever will.
Rockstars are not created by market pressure. Therefore there is no asset bubble for their services waiting to pop. You and I can safely sit here and dream up ways to lift up the entire profession because it won't get stolen out from under us by ninjas.