The issue with the FPGAs are that the ones discussed are expensive development kits that are designed for giant companies to use for development and evaluation. They aren't mass produced and meant for general public consumption, and are priced accordingly. Mining is not driving them up in price. Also anything that is meant to go into data center is going to be much more expensive than consumer products. I might end up eating my words but personally I think anyone buying a VCU1525 for mining is going to be in for a rude awakening and a lighter wallet.
As far as render rental, it will be interesting to see how this ends up, but ultimately I don't think it will be that profitable. Kind of like SIA, its a day late and a dollar short; AWS, Google Compute, and Azure already offer this service. It will be a race to the bottom to offer lower prices then them.
Oftentimes the devkit for an FPGA will be less expensive than the actual FPGA. A cursory search of the
VCU1525 on the Xilinx website says it uses the XCVU9P-L2FSGD2104E Virtex UltraScale+ FPGA which has a single unit price of $47000US at DigiKey, Avnet, etc. Yes, that's $47k for just the IC...
So, I'm not thinking the FPGA threat is all that serious and do very much think that Xilinx will radically increase the price of the devkit if they sell even a few more than predicted, especially outside of the usual channels; customers contemplating the use of such an expensive IC will expect - and get - a lot of handholding from Xilinx.
You are looking at retail prices. Companies buying these chips en mass from Xilinx get a very steep discount. I mean other companies are making boards with these and I guarantee they aren't spending 50k on a chip: Senseless on the forum custom made a board with these chips, notice the price?
$3500. Currently the dev board is selling for $6500 on avnet.
I mean FPGAs aren't a threat in the sense that they obviously aren't readily available to the average consumer who hasn't done their homework and still difficult to buy if you know. We aren't going to see FPGAs rival GPUs in quantity but a little goes a long way with these.