@Cleverhash

In your shared PoW/PoS system with 0 block rewards and 0% stake reward, what measures are in place to ensure there's incentive for users to support the blockchain with sufficient power to withstand a concerted 51% attack?

It may be that the answer to this is obvious and I just don't understand PoW/PoS well enough. However, this question has been asked before and never answered.