I'm bullish on proof-of-stake. I don't think proof-of-stake will replace proof-of-work, and I don't believe in the other way around. I think it will live alongside it.

Many corporations is another way of achieving decentralization. I see proof-of-stake as a corporation that is run by multiple nodes, and the block reward is paid to the stakeholders. Lazy stakeholders (don't provide witnessing, don't relay information, don't do anything) or faulty stakeholders (can't keep their own servers secure, letting hackers take control over it) can be punished with slashing (losing stake, thus making other stakeholders that do a good job increase their influence over the corporation). In fact, with Bitcoin, the node operators are paid NOTHING, even though they provide a vital service for the network.

For those that have an absolute distrust for all corporations, proof-of-work will exist alongside it. Gold is an apolitical metal. There is no need to trust any administration or government to check that gold is gold. Proof-of-work, with its greed-based incentive (the miners are being bribed with the block reward to prevent reordering of the blocks in the chain) allows for decentralized consensus that does not rely on the quality of the stakeholders of a corporation. As long as miners stay greedy, PoW should work fine.