check this articles. some core developer may not contribute frequently. such as CJentzsch, tgerring, gavofyork. I hope ethereum could attract more talent and continuous grow, especially speed up pow -> pos transition. How the miner will react to future event, move away quitely to other mining project?
Well in retrospection it all looks good and with more and more development I think ETH performance should better. Its been a few days since the Byzantium hard fork ..