While WotC has indicated that any third-party licensing announcements (if any) will be coming in early 2015, some publishers have moved ahead with D&D 5E compatible projects of their own. Some have used the Open Game License to access terms and phrases associated with D&D, while others have taken a different approach to the legalities. This article isn't about those legalities, because I'm not a lawyer. But if you're looking for additional content I've highlighted some stuff currently available.
DriveThruRPG (and RPGNow) has a selection of D&D 5E products
in their own section on the site, some from WotC, others from third party publishers including Mithgarthr Entertainment, Genius Loci Games (which refers to "5Next Edition"), Goodman Games, Hack & Slash Publishing, Silver Gryphon Games, Tripod Machine, and Sacrosanct Games. In total there are 11 5E products there; I haven't tried any of them, though, so I can't comment on their quality (I do have hardcopy versions of the two Goodman Games books, though, which Joseph Goodman kindly gave me at Gen Con).
I asked Steve Wieck of DTRPG about the site's policy on third party products and licenses, who kindly answered:
"Publishers who upload titles with us may select any rule system category for their titles they feel are appropriate.
To date we have received no requests to take any action related to any titles available on DriveThruRPG that are listed in the 5e rule system category.
Our "policy" on most things related to operating DriveThruRPG is to have as few policies as possible."
Third party PDFs at DTRPG
Kickstarter is another place to find third party products for D&D 5E. I have reported a few times on Necromancer Games' successful "Back for 5th Edition" Kickstarter
which ended a while ago. This Kickstarter funded three 5E books in total - a monster book, a book of short adventures, and a book of spells.
Necromancer Games' Kickstarter