Nellisir
Hero
Skyrim isn't closed content, because closed content only occurs within an OGL work.I don't understand your comment about Skyrim. 'Dragonborn' would be 'closed content' and closed content is not covered by the OGL... so I'm not sure how using it would affect how someone interacts with closed content?
Example: I write a book. All proper names (Janiem, Mariel, Gertren, Dennir the Dane, Svingelland) are declared Product Identity wheresoever they may occur in the work. Chapters 2 and 7 are declared Open Game Content.
So you can only reuse stuff from Chapters 2 and 7. Chapters 1, 3,4,5, & 6 aren't PI, but they aren't Open Game Content either - they're closed content.
Works that don't use the OGL don't have OGC or PI, and so they don't have closed content. It's like asking how much lobster is in the number six.