Was there ever an intention to bring Blade into the MCU before Wesley Snipes had to go to jail? Was it always meant to stay separate? Or are there plans to incorporate Blade into the future MCU?
There were no plans before Snipes went to prison. Marvel couldn't have made a Blade film until sometime around 2012 when, according to The Hollywood Reporter, the film rights reverted to them from New Line Cinema:
More recently, Marvel welcomed Blade back from New Line, which made a trilogy starring Wesley Snipes as well as a TV series.
Any plans for a new Blade film were not publicized, and couldn't have included Snipes in any case. The actor had been convicted and sentenced for failing to file federal income tax returns, and officially began his sentence in December 2010; he wouldn't be released until 2013, making feature film appearances difficult.
Of course, there have been more-or-less perpetual rumours about Blade's MCU induction ever since his release. One of the more notable was a 2015 interview with IGN, where Snipes said:
Marvel and I have decided to have further conversations. It's a topic of conversation. It's inescapable. They have their agenda, we have ours, and we're both moving at an accelerated pace to create magic. We'll see if it all matches up. There's a strong possibility
And, on a panel at New York City Comic-Con in October 2016, actress Kate Beckinsale allegedly confirmed that something involving Blade was underway at Marvel Studios:
[S]omeone asked if there was any chance of seeing a crossover involving her vampire hybrid character Selene and Blade. Here's what she had to say:
"No. We had that idea. No. They're busy. They're doing something with Blade."
In response to this rumour, Marvel Studios president Kevin Feige clarified after the Doctor Strange sneak peek in October 2016 that they haven't forgotten about Blade, but that there are no immediate plans:
They did ask a long time ago, and I think our answer was, 'No, we'll do something with Blade at some point.' That's still the answer. [...] There is nothing imminent to my knowledge.
However, whether or not they ultimately bring Blade into the MCU, there's no guarantee that Wesley Snipes will make the trip; Marvel's usual pattern with characters they regain the rights to has been to recast as they see fit; for example:
- Daredevil went from Ben Affleck to Charlie Cox
- In the same series, Elektra went from Jennifer Garner to Elodie Young
- The Punisher went from Ray Stevenson to Jon Bernthal
- The Hulk went from Eric Bana to Edward Norton (and then Mark Ruffalo, just to mess with your flowcharts)
- Ghost Rider went from Nicholas Cage to Gabriel Luna1
- Luke Cage went from... well, nobody2 to Mike Colter
1 Although they also switched who was behind the Spirit of Vengeance, so this isn't really a terribly fair assessment; Cage played Johnny Blaze, the traditional (and first) Ghost Rider, while Luna plays Robbie Reyes, a relatively new addition to the comics
2 Columbia Pictures was shopping a Luke Cage movie around since 2003; although the lead role was never cast, such luminaries as Jamie Foxx, Tyrese Gibson, Dwayne "The Rock" Johnson, Isaiah "Old Spice Guy" Mustafa, and Idris Elba had expressed interest. Of course, this was before the rights to the character reverted to Marvel in 2013.
Marvel is finally bringing Blade into the MCU in Phase 4 or 5. Mahershala Ali will be starring as Blade, for more information this Den of Geek post is quite thorough.