Frankly I'm quite happy about "fake news" proliferating, it makes obvious how hopeless and useless news orgs are. They peddle claptrap and tripe with reckless abandon.
Facebook could throw ten thousand engineers at the problem and 1) it wouldn't fix that nobody trusts Facebook 2) it wouldn't fix that nobody trusts news orgs. Fox News' "Fair and Balanced" slogan needs to taken as religious dogma -- everybody gets as voice and Facebook has no say in who can't speak.
To any news tweeps reading: combating "fake news" by partnering with Facebook is a partisan attempt at self-fellatio -- all you do is get yourself off without accomplishing anything. Conduct real journalism with well-paid staff that have the time to do their job and anonymously share it with the public is the only way to restore trust, not 1) procuring access to high-value talking heads (eg: celebrities, pundits, "experts") that will regurgitate your propaganda or 2) shoving out unverified garbage (eg: 99% of reporting on Trump this past election cycle) at light-speed.
#1 is just a sad attempt at remaining relevant while having someone authoritative make an empty appeal to viewers and #2 is plain laziness.