There is interest (e.g. from The Trust Project, and conversations around fact checking and our ClaimReview markup #1061) in using schema.org to describe more detailed kinds of NewsArticle, such as allowing sites to express that an article is an opinion piece, a backgrounder document, analysis, visualization, or that it is sponsored content. We have also touched on these themes here recently when discussing the idea of a 'Satirical News Article' subtype, see #1437.

See also https://www.theatlantic.com/technology/archive/2017/05/what-people-really-want-from-news-organizations/526902/

In the simplest case we could overload the "genre" property here, but I'd suggest (repeating myself from #1437) that a bit more structure will be more rewarding in terms of markup usability / quality. We could use a simple Enumeration list but I lean towards types since they can be instantiated (to carry properties) and even subtyped further. More compellingly, in the (increasingly popular) JSON-LD format, markup for types is simple, and even multiple types also a simple array of short tokens, whereas in general our markup for enumerated property values involves full URLs and is more error prone.

Update (May 10th) from @danbri:

Several results of these investigations:

• Proposed new definition of NewsArticle to replace "A news article".
• Added several (pending) subproperties of http://schema.org/publishingPrinciples
• Tweak to publishingPrinciples - see /publishingPrinciples describes organizational principles, should be applicable to Org #1601 - to allow organizations/persons directly.
• New subtypes for NewsArticle, again pending: AnalysisNewsArticle, BackgroundNewsArticle, ReportageNewsArticle, OpinionNewsArticle, ReviewNewsArticle.
• New Article types alongside NewsArticle: SponsoredContentArticle, SatiricalArticle.
• A "News overview" document describing these, http://webschemas.org/docs/news.html