this is a long-run / short run criterion. but it is frankly irrelevant and trumped by the OP's analysis. the shortage of STEMs is a myth. People with those skills don't per-se want those jobs. Its like gulf-arabs. They need to import labour to clean their toilets. There is not a "shortage" of skilled labour in the houskeeping sector. At least not in any normal sense.
If no one wants to do a job at X price, it is then by definition a shortage.
Neoclassical economics suggest moving up the price ladder. But as a comment above mentioned, STEM job supplies are quite inelastic. In fact we should expect it to be inelastic, since STEM jobs require more expertise than say general labour.
there are other options any fixed price x(i): no trade (not one), and equilibrium (no more). If X is floating, the question is different. Then its a question of why X wages are not enough. Its also a question of why the jobs are not made better (not everything is price related, the firm is a hierarchy...). etc.
