Elon Musk keeps talking about the subject and will attempt his own project, PRAVDA.
I have been working on a similar blockchain-based concept (still in early stages) since late last year. The main challenges for a project like this is to set up a trusted decentralized reputation/voting system or data aggregation point reputation system that pulls reputation/truth score data from a range of sources, then put that on an immutable blockchain and incentivize people to use it and share it. The main thing I see a project like this needs is protection from being easily corrupted, gamed or becoming centralized in the future. The second thing would be building awareness.
What do you guys think about the need for Decentralized News Media? How would you think it could actually work?