Earlier quoted context omitted.
FPGAs may have opened up options for prototyping, yes. However they have done nothing whatsoever for production. It's economically infeasible to productize and FPGA based product since the only ones worth using are all ~$10k per unit, with price breaks only available to 1M unit quantities. It is also almost entirely impossible to commercialize any design with an ASIC, since it takes a minimum of $10-20M to design it…
Sure, but in the past you would not have gotten to 'demoable product' which is a key post to pass on the road to serious funding in the hardware arena.
If it's a hot hardware area (past hot areas: graphics chips, microprocessors, WiFi chips, OC-768 networking chips, ...), nobody will wait for the FPGA prototype. You get funding, you go to VLSI and maybe you produce an FPGA board for validation along the way. Probably not since what you're doing is probably too complex for a single FPGA anyway.
Otherwise, your volume is too small and the FPGA IS your product.
And that's only if you can't somehow make it run on a microprocessor.
The only place I've ever seen an FPGA validation board was with RF startups in the cellular space. And, even then, it was way back when the protocols were much simpler.
tl;dr If your demo doesn't run on a microprocessor (or SoC), it doesn't exist.