Tony Vargas
Legend
Paizo publishes Pathfinder, which is a d20 OGL game. It's not technically producing tons of adventures and other cool stuff for 3.5 D&D, but for Pathfinder, which is a clone thereof. FWIW.Pathfinder isn't a 3rd party publisher for D&D anymore, they're a 1st party publisher of their own game.
I saw a "5E" branded adventure produced by a 3pp. It wasn't even that bad, I found it a little evocative of older classic D&D adventures. It wasn't technically being sold, it was at Free RPG Day, but there have been a few such things produced. It was published under the 1.0 OGL, and assiduously avoided saying it was for 5e D&D, saying, instead "the Fifth edition of the First RPG," and with it's own 5E-in-a-pentagon logo, instead of the 5e ampersand.I am of course referring to the third-party publishers who wish to sell *5E* material... which should have been blatantly obvious.
It probably doesn't matter if there's ever a 5e OGL or not - 5e is similar enough to 3.x/d20 that the old OGL works.