This is the same problem being mulled over with my coin.  (Search RPCD ANN)

According to my analysis Bitcoin has incentives to centralize as market cap goes up, especially as long as block rewards are relatively high. You can't risk orphaned blocks mining on your own little home based node and p2p pool doesn't seem to be as efficient either.

Where with DPOS it seems all the centralization should occur early on and then as market cap grows, the largest reason for multiple delegates per person decreases because each can pay a fair amount of compensation. At that point shareholders (which POW miners are not) will be incentivized to keep the network decentralized because NETWORK SECURITY WILL DEMAND IT !