I know this sounds vague and I have a specific example in mind, but I thought a more open and general discussion would be more helpful.
On taking requests for my upcoming cultural TL I have run into a lot of people wanting to increase the popularity or cultural legitimacy of certain fictional genres dear to them. Science fiction, Sword and Sorcery, and High Fantasy foremost among them.
I personally would like to see all these, (and add steampunk to the list) however, I feel like there is first of all not enough popular subgenres of each and secondly few opportunities in literary or cinematic history for these to come about earlier and/or with a larger fanbase.
This got me thinking about altering certain subgenres of fiction and examples of said fiction to provide a springboard for them and some interesting ideas came to me that I wanted some feedback on, as well as hearing your own thoughts on alternate genres and more popular subgenres.
Here's my entry:
It seems that Sword and Planet/Science Fantasy could have been a much broader and more inclusive subgenre, and even a bigger genre in and of itself, and could even make way for an earlier steampunk incorporated within it. I thought of having Tolkein become something of a Science Fiction fan and write a very different (but at least equally popular) version of the Hobbit and the Lord of the Rings with combined elements of Space Opera, Steampunk, Science Fiction/Fantasy, High Fantasy, Sword and Sorcerer, and Sword and Planet thus creating a new genre which satisfies all the requests I received and catapulting this new hybrid genre into massive popularity. (Who knows? Lucas may get the bug to direct this Space Opera LOTR instead of Star Wars... hmmm...

)
A. What do you think of this example?
and...
B. What are some other examples of alternate fiction genres and more popular or broader subgenres from OTL?
I think, if this OP was clear enough (and it may not be...) we could have some fun with this subject.