From what i see so far, people that are working on fpga miners are wanting to keep it private for now which make sense. I did some small research, its viable to mine with today's fpgas you dont have to use top of the line fpga though, even mid range fpga's offer good options for mining.
 
Intel recently started to offer opencl sdk that can compile opencl code to Altera/Intel fpgas (not for all models) in my opinion this is a game changer you dont have to mess with tedious VHDL or Verilog code. If someone is more interested about this there is an article about it in this magazine https://software.intel.com/en-us/download/parallel-universe-magazine-issue-31-january-2018