The solution to Fake News is to minimize its effect on Consensus. In particular we want to minimize the potential for Fake Consensus (e.g. polling results) because of the impact that Fake Consensus has on people's actions.
If we can provide provable consensus then we will have eliminated a large and dangerous category of Fake News and replaced it with truth. This consensus may still be centered around a falsehood, but at least it accurately reflects what people think.
When we don't even know what other people think, that is when the complete breakdown of communication occurs and society is in trouble.