Although many people cite Christopher Nolan and Batman Begins as creating the idea that comic-book movies could be more adult, it was really Stephen Norrington and Blade that were responsible.
In 1998, Wesley Snipes was in a purple patch and took on the character of Blade, a half-human / half-vampire who violently offed vampires which were led by rave-loving Stephen Dorff. Man, the '90s were weird.
Anyway, fast forward to the third installment and you've got Triple H and that guy from Prison Break starring in it and it's directed by a screenwriter on his second film. The story surrounding Blade: Trinity is a fascinating one that's been covered before in other formats; the TL;DR being that Snipes was an egomaniac and Goyer hired bikers to protect himself on set.
Since the success of the Marvel Cinematic Universe and, more pointedly, the more adult-tinged Netflix / Marvel Television adaptations, Blade has always been bandied about as a possible option. For his part, Wesley Snipes was up for reprising the role and, even more recently, Kate Beckinsale (?) let it slip during a red carpet interview that another Blade film was in the works.
That, however, is not the case according to someone who'd actually know - Kevin Feige, Marvel's high overlord emperor. In an interview with The Playlist, Feige repeated the party of line "Maybe, but not now", in so many words.
"We still think he’s a great character. He’s a really fun character. We think this movie going into a different side of the universe would have the potential to have him pop up, but between the movies, the Netflix shows, the ABC shows there are so many opportunities for the character to pop up as you’re now seeing with Ghost Rider on ‘AGENTS of S.H.I.E.L.D.’that rather than team up with another studio on that character, let’s do something on our own."
"What that is? Where that will be? We’ll see. There is nothing imminent to my knowledge."
To be fair, it doesn't seem all that plausible that Blade could fit in with the current Marvel setup. After all, the entire MCU has to come in at 12A or lower in order for it to hit the widest possible audience. If they decided to go down the Fox / Deadpool route, sure it could work, but that seems highly unlikely to fit in with Disney's culture.
Still, who knows? Nobody ever expected a Jessica Jones / Daredevil / Luke Cage / Iron Fist crossover series and we're only a year away from that, so anything's possible.
Via The Playlist