I hear what you’re saying… I think you’re confusing centralization with the concept of simply having larger shareholders.
Anyone can and will always be able to stand up a Zcash node (decentralization), allowing P2P broadcast events to flow throughout the network, as well as verifying transactions.
We’re already seeing large/farm size GPU mining setups aimed at Zcash, as well as the stratum implementations being sold off (not free is the point). Having an FPGA implementation is simply the next evolution; especially when efficiency is concerned.
I know of a Decred FPGA solution that has been around for nearly a year now, i’m sure there would be quite a few now.
Having a large network presence is beneficial for the actual users of Zcash; because it means transactions will be confirmed quickly and with a high level of security as the difficulty increases.