Well, as I understand it, the Obskurakorps are a subsection of the Ahnerbe, a la the GOC and the United Nations, while the Thule Society and the Nazis proper were - things that existed. OBSKURA tends to be the most prominent simply because it's the most identifiable, unique, and cumulative of the four.
As for the SS becoming a GOI as a point of fact, we've already got a group bent on global cosmic reconfiguration, some enormously amoral venture capitalists, and a Church bent on resurrecting a/some mechanical apocalypse gods. The wiki is no stranger to things which are eldritch, nonsensical, and/or generally horrible. Besides which, I'm pretty sure we tend towards OBSKURA being decidedly not strictly in line with Party doctrine, more along the lines of the Chaos Insurgency's 'mankind must ascend to the one true form' shtick - though, of course, they still find their origins in the depths of National Socialism.
All of this, however, is somewhat moot at this point seeing as how I was a tit and jumped the gun as per usual. I think this'd be a more relevant conversation to engage in if and when we see der Fuhrer rise to his fifth article.