If the mining reward was suddenly changed to 0, and there were no mining fees anymore, what would happen with the Bitcoin network? Assume there is another anti-spam measure in practice (ex: a tx would need the last block hash + some small PoW on top of it). Would Bitcoin suddenly collapse and get unusable, would it still operate normally due to voluntary mining?

  • Possible duplicate of What will happen to mining after the 20 999 999th Bitcoin? – Jestin Jan 9 '17 at 22:03
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    I marked this as a duplicate because it's not a matter of if, but a matter of when, and there's already some good answers. – Jestin Jan 9 '17 at 22:05
  • @Jestin you're right, but my question was incomplete. I actually meant to ask what would happen if we removed any kind of mining reward, including fees. Basically, it is a thought experiment on which I want to know if the network could still operate safely solely with voluntary mining. I edited the question, could you remove the duplicate flag? – MaiaVictor Jan 9 '17 at 22:09
  • in that case this question may be a little to speculative for Bitcoin SE. This forum is best for questions with concrete answers, and not so great for thought experiments, speculation, or debates. It's too hard for the community to determine what a "good" answer is. – Jestin Jan 9 '17 at 22:15
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    This question is not useful. The reward is part of the core assumptions of Bitcoin that you might as well be asking what would happen to Bitcoin if there were no internet. – Murch Jan 10 '17 at 13:21

Even though they are still somewhat negligible to miners today, transaction fees play an important role in the protocol known as Bitcoin, and will play an increasing role in the future. Just look at all the questions this SE site gets about unconfirmed transactions. Asking how the protocol works when removing all direct mining incentives is redefining the protocol in a major way. It's like asking how HTTP would work if you remove the verbs from the protocol. At that point, it's something completely different.

When you remove such a critical part of the protocol, it's difficult to replace with something that works. For example, your proposal of doing a proof-of-work on top of the last block hash as part of the transaction will effectively break the ability to use the protocol for smart contracts.

You are essentially asking what happens if you remove critical parts of Bitcoin, but still use the basic idea rather than creating a new protocol to match your paradigm of no mining rewards. To that, I can only speculate that such a system is doomed for failure.

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