Right now the number of these FPGA's (in the world) that are actually available is about 500 (taking into account high-current boards only). So even if someone wanted to 'monopolize' this technology they could not.
Later this year, 5000-9000 boards will enter the market. It will be late 2019 before 25,000 boards are even manufactured. By then, the crypto market will probably have doubled or tripled, which means the number of supported FPGA's also doubles or triples. So it is not clear that the FPGA's can ever catch up to the market.
Your '500' is very low. 5000, and possibly more, of the 1525 variants will enter some sort of operation within the next few weeks. This is gonna be a race until the rigs become unprofitable.
I would add that the secondary market for these boards, once rendered unprofitable for altcoin mining, is nil.
PS -- The '300A' Bittware card is a single FPGA? VU13P maybe? Seems like overkill.