I've seen calls across the web, like this one, for a standalone Loki movie. I am not on board with that at all.
Don't get me wrong: I think Tom Hiddleston is a great actor, and Loki is a very interesting, complicated villain. However, I'm going to argue that we don't need Yet Another Marvel Movie About A (White) Dude.
According to wikipedia, these are the solo Marvel movies made since 1998, including movies currently in production/planning.
2002 Blade II
2004 The Punisher
2007 Ghost Rider
2008 Iron Man
The Incredible Hulk
Punisher: War Zone
2009 X-Men Origins: Wolverine
2010 Iron Man 2
Captain America: The First Avenger
2012 Ghost Rider: Spirit of Vengeance
The Amazing Spider-Man Columbia Pictures
2013 Iron Man 3
Thor: The Dark World
2014 Captain America: The Winter Soldier
The Amazing Spider-Man 2
That's 26 solo hero movies, only one of which stars a female hero (Elektra, 2005, which was reportedly a terrible movie). Twenty-five male-led superhero franchise movies. Twenty-five. If we just stick to the Avengers, there are nine. And is anyone seriously excited about an Ant-Man movie, starring serious asshole Hank Pym?
I get it. People love Loki because he's a giant woobie and Hiddles is cute and ridiculously talented. That doesn't earn him male-led movie number twenty-six.
The first page I linked to has links to petitions for a Loki movie and for a female-led superhero movie. The Loki petition currently (11:51 am 11/16) has 35,526 signatures. The female-led one? 275, and the hero on the cover is Sif.
Forty percent of the CIA's operatives are women. Black Widow is popular, though not as popular as Woobie-Destroyer-of-Worlds-Loki. A post which asks tumblr users to reblog if they think Black Widow should have a solo movie only has 3462 notes. This post, in which someone imagines a Black Widow trailer hijacking a "Loki" trailer has 29,500 notes, but humorous posts get a lot of notes on tumblr.
One popular reading of Joss Whedon's "The Avengers" was that it's Black Widow's movie, because she basically carries the story. If an ensemble movie starring a team of five (white) dudes and a lady (plus Coulson and Fury and Hill, but they're not The Avengers) is the best we can hope for a female hero movie, that is bullshit.
It's 2013. Movie studios no longer have the excuse that female-led action movies don't appeal to a broad audience (read: 18-25-year-old white males, who aren't even the biggest movie-going demographic, but that's another rant altogether). Strictly speaking, Sigourney Weaver (Alien) and Linda Hamilton (Terminator) proved them wrong back in the 80s, but this little movie about a girl named Katniss Everdeen, maybe you heard of it? The sequel's coming out this week? Yeah. And there are more. (Hanna. Oh god that movie.)
So why the fuck NOT have a Black Widow solo movie, where she's leaving the KGB and coming to work for SHIELD? Give me Natalia Romanova or Natasha Romanoff, spying, kicking ass, infiltrating, and being a goddamn HBIC. Or, if Hollywood requires a man in action movies because of bullshit reasons, I would settle for Clint and Natasha being snarky and competent, spying and kicking ass together. Or even a "when Natasha met Clint and they had to learn to trust each other and work together" movie. And they never sleep together, because god can't we just have a movie about a man and a woman who are friends but not lovers?
There has been a massive discussion about inclusivity in media (comics, movies, novels, games) and in fandom, and how fandom isn't welcoming to people who aren't (straight) white men. Supporting Yet Another Movie About A (white) Dude does not promote inclusivity, does not welcome women into fandom.
Yes, I certainly enjoy looking at Chris Hemsworth's biceps and Chris Evans' pecs, and I can't deny that attractive male actors are a draw. But I don't want to BE Thor or BE Steve Rogers. They aren't characters I can identify with.
When I see Scarlett Johansson on screen as Black Widow, I see a character I could fantasize about being. I've said that I want to be Black Widow when I grow up. I can identify with her. In Iron Man 2, she's patronized. (and this version has even better commentary.) She's probably had to put up with a lot of that shit in her life, as a relatively diminutive woman.
So, in conclusion, women also watch action movies for escapism, and you should support a female-led MCU film (especially if it's Black Widow) before a Loki movie.