The rumor that Anthony and Joe Russo - directors of Captain America: The Winter Soldier and next year's Captain America: Civil War - are all but set to helm The Avengers: Infinity War - Part 1 & 2 started making the rounds even before Marvel Studios had announced that Avengers 3 and Avengers 4 would take on the form of a two-part adaptation - one that will incorporate elements from the "Infinity War" and "Infinity Gauntlet" comic book storylines, by the sound of it.
Infinity War is when the 'Mad Titan' himself, Thanos - as brought to life by Josh Brolin in the Marvel Cinematic Universe - and his quest to take control of all six Infinity Gems (via his Infinity Gauntlet) will move to the forefront, after having been gradually developed over multiple films, beginning back in Phase 1 of the MCU. It will be a huge event, in other words, and has the potential to easily fill out the running time of two Avengers movies - so, it would make sense for Marvel to recruit not just one, but two of its accomplished collaborators to handle the job, too.
The downside of this Infinity War rumor, of course, is it means no Joss Whedon in the director's chair, after he wrote and directed The Avengers - a box office smash and favorite with critics and fans alike - and this year's sequel Avengers: Age of Ultron, which could well match or exceed its predecessor's accomplishments.
Going off comments that Whedon made during an interview with Empire (via CBM), it might be for the best that he step down now - lest he suffer creative burnout while overseeing two more Avengers movies.
"I couldn't imagine doing this again. It's enormously hard, and it [will] be, by [the time I would make 'Avengers 3 & 4'], a good five years since I created anything that was completely my own. So it's very doubtful that I would take on the two-part Infinity War movie that would eat up the next four years of my life. I obviously still want to be a part of the Marvel Universe - I love these guys - but it ain't easy. This year has been more like running three shows than any year of my life. It is bonkers."
This is the first time Whedon has commented on the idea of him directing the Infinity War films since they were officially announced. It makes sense that he would want to step back a bit at this stage, fresh off having served as one of the MCU's chief creative architects through its second phase - including, writing/directing two Avengers movies and co-creating the Agents of S.H.I.E.L.D. TV series - and get back to work on smaller, original projects of his own design. (That long-rumored Dr. Horrible's Sing-Along Blog sequel could even be among them...)
Then again, there's no reason Whedon cannot still be involved with, say, helping to craft the scripts for the third and fourth Avengers installments, even if he passes on taking the helm. Writing has always been Whedon's forte as a storyteller anyway, more so than his work as a director - though, he's clearly stepped up his game for Age of Ultron - and even if Joss doesn't serve as the sole writer on the Infinity War movies, they could certainly use his help (given how many different plot and character threads those films will have to tie together).
Meanwhile, the Russos have arguably been responsible for the best filmmaking in the MCU to date, between the modern-day political thrills offered by The Winter Soldier and the 1940s pulp throwback style of their work on the Agent Carter limited series - and chances are, their sense of moviemaking craftsmanship will only continue to improve, once they've completed work on Civil War in 2016, preparing them to tackle a MCU storyline that's even bigger in scope and stakes. Should Infinity War - Part 1 & 2 combine these forces (with the Russos directing from scripts co-penned by Whedon), that could be an ideal outcome for everyone involved.
However, even though the signs currently point to the Russos directing the Infinity War movies, for the time being no deal has been officially struck. Similarly, there has been no indication yet that Whedon is being eyed to write these films - much less, that he's necessarily interested in the job. There's still very much room for another creative voice to step in and help guide the screenwriting process on the third and fourth Avengers installments, instead.
That said: Marvel Studios clearly prefers to draw from in-house talent (having found great success in doing so thus far) - and Whedon has made it equally clear, he doesn't intend to leave his Marvel days behind him (not completely, anyway) just yet. So don't be surprised if Joss ends up playing a role in the telling of the cinematic Infinity War, in turn paving the way for the most accomplished talent on the Marvel filmmaking roster to join forces for this major venture.
The Avengers: Age of Ultron releases in theaters on May 1st, 2015, followed by Ant-Man on July 17th, 2015, Captain America: Civil War on May 6th, 2016, Doctor Strange on November 4th, 2016, Guardians of the Galaxy 2 on May 5th, 2017, Thor: Ragnarok on July 28th, 2017, Black Panther on November 3rd, 2017, Avengers: Infinity War – Part 1 on May 4th, 2018, Captain Marvel on July 6th, 2018, Inhumans on November 2nd, 2018, and Avengers: Infinity War – Part 2 on May 3rd, 2019.