What you are missing is the marginal production costs. I would guess that now that they are masked out, the chips cost $10 a piece and the USB boards with heatsink (for example) cost another $10. Current price is 2BTC. There is a huge decrease in price that can be made and still be profitable. As competitors come online only one thing will matter: who can source their chips and boards the fastest.
that's where having the facilities and experience of producing 300 TH rapidly actually counts for something.