I know I'm coming to this thread a bit late (a bit??), but I've noticed cuckold porn is MUCH more popular and plentiful lately. It used to be a fringe fetish in which (mostly) Black men would fuck (mostly) White women as their (mostly unknown) needle-dicked husbands or boyfriends looked on in horror. Now, there's an explosion of cuck porn, and it includes mainstream actors and actresses in all the roles.
I recently saw a cuck video with Evan Stone fucking a chick, and then some random guy eating his cum out of her cream pie pussy. Not long ago, that would never have been considered by a mainstream porn actor for fear that he'd be accused of having crossed over into gay porn ("A guy ate his cum??! That's so gay!"). But now, it seems to be perfectly acceptable.
You'll all think I'm' crazy for saying this, but I think it was the Alt-Right who created this phenomenon. During the run-up to the presidential election, Trump supporters started using the word "cuck" to refer to Hillary Clinton supporters. This seems to have made people Google the word "cuck," and discover cuckold porn. I have no proof, but it seems plausible. Guys got turned on by it, and the demand led to more of it online. That's my theory, anyway.