The Inhumans Theory
We already know that Age of Ultron will involve a secondary villain in Baron von Strucker (played by Thomas Kretschmann). In our own analysis, we predicted that Strucker will be a villain early in the film - most likely employing the powers of Quicksilver and Scarlet Witch for evil purposes, before the threat of Ultron eventually pulls the twins over to the Avengers side. Some recent revelations about the Captain America 2 post-credits scenes may lend credit to parts of our initial Strucker speculation - but UTF is taking things a step further by reiterating a rumor we ALSO speculated on during the early stages of Age of Ultron's development.
WARNING - THIS RUMOR COULD BE A MAJOR SPOILER FOR MARVEL MOVIE FANS!
According to UTF, they have sources now confirming that Quicksilver and Scarlet Witch will both be cinematic versions of Marvel's Inhumans, rather than mutants. If you're not aware, Fox (the studio which owns Marvel's X-Men and Fantastic Four brands) also owns the whole idea of "Marvel mutants," which is why Marvel Studios CANNOT use that term or idea in their films.
Traditionally, Quicksilver and Scarlet Witch are the mutant offspring of Magneto (a character that is, again, owned by Fox), so to be in Avengers 2 they need new origins and new explanations of their powers. Super soldier experiments, deities, and tech-enhanced warriors have all been done - and based on the revelations of the Captain America 2 post-credits scenes (which you can read at your own risk), it seems Marvel Studios could be re-branding mutants in a way that better fits their movie universe.
If the original Avengers exposed the possibility of super-powered beings to the world, then it's only logical that further possibilities for super-powers would be explored by both good and bad factions within the MCU. With the Thor and Guardians of the Galaxy franchises revealing a whole big universe out there, The Inhumans are an easy way to explain how super-beings (and powerful artifacts/weapons) exist, while also binding together the earth-bound and cosmic films in the Marvel Cinematic Universe.
For those who aren't familiar, The Inhumans are a species of super-powered beings who were created by alien experiments on prehistoric humans. These "Inhumans" lived in secret until their presence (on the moon) was discovered. The key here, is that the aliens who created The Inhumans are the Kree - a species which will be featured in Guardians of the Galaxy, as that film's villain, Ronan the Acuser (Lee Pace), is a Kree enforcer.
See how this all intertwines?
We know that Thanos is still a big bad hovering over the entire Marvel Cinematic Universe - and that his cosmic war could be fought in Avengers 3. If Thanos has Kree henchmen, then the history of that species could filter into other Marvel projects any number of ways - creating
mutant super-powered characters being an easy one. If Kree tech infuses humans with superpowers, we would therefore also have an easy explanation for how characters like Captain Marvel, Ms. Marvel or other "cosmic heroes" get created.
The Inhuman origin story could also easily be updated to focus not on prehistoric humans, but rather modern genetic experimentation on humans using the discoveries of alien DNA. In fact, Agents of S.H.I.E.L.D. has already introduced a plot thread involving characters like Coulson and Skye being infused with DNA from an unknown blue alien-looking creature; that creature could easily be revealed as a Kree (big and blue-skinned), tying AoS to events that could lead into Avengers 2.
All in all, it seems like UTF's sources could be on the money with this latest theory. We'll find out more in the coming year, no doubt.
Captain America: The Winter Soldier hits theaters April 4, 2014, Guardians of the Galaxy on August 1, 2014, The Avengers: Age of Ultron on May 1, 2015, Ant-Man on July 17, 2015, and unannounced films for May 6 2016, July 8 2016 and May 5 2017.