Note, potential SPOILERS for a whole bunch of future Marvel related stuff, and a fair few old comics.
Iron Man 4 is a long way from our screens. A really, really long way. Two whole Avengers movies away. At least. But eventually, it will come. Kevin Feige, Marvel Studios' head honcho, says it will, so it might as well be gospel.
And that means we can start to work out what it'll be about.
Feige has admitted that:
¨There will absolutely be future Tony Starks and future Iron Mans. Who makes those movies, and when those movies are made, who knows?
Which opens up a whole universe's worth of possibilities.
If Tony Stark is to blame for The Age of Ultron, will we finally see the infamous alcoholism storyline?
In the comics, Hank Pym (aka Ant-Man) is to blame for the creation of Ultron.
With the casting of Michael Douglas as the character for the upcoming standalone Ant-Man movie, it would make a lot of sense that we'll see this storyline in The Avengers: Age of Ultron, too. Except for the fact that Joss Whedon has said that we definitely won't.
Which leaves Ultron in need of a creator - and Tony Stark in the position of resident Marvel Universe tech genius. Add into the mix Paul Bettany's role as the Vision - suggesting a direct link to his role as Stark's computer sidekick J.A.R.V.I.S. - and there's a fairly compelling argument that Stark is going to be inadvertently responsible for - not-actually-a-spoiler alert - the rise of the incredibly destructive Ultron.
Which will be a whole bunch less than fun for Tony. Could the aftermath of such a traumatic event fundamentally change the Tony Stark character - and potentially give him a character arc Robert Downey Jr would be interested in pursuing for one last standalone movie?
If so, then this is what that'd look like:
The legendary 'Demon in a Bottle' storyline, in which Stark often unsuccessfully battles alcoholism, was almost included in Iron Man 3, and was reportedly only vetoed for confusing the Mandarin-heavy plot. It would be brutal viewing, but also exactly the sort of thing that Robert Downey Jr is fully capable of making into something incredible.
If the Guardians of the Galaxy film does well, will Tony Stark head to space?
Marvel has recently gone through a pretty fundamental relaunch of some of its major titles - and when the Guardians of the Galaxy got their own new title, they also picked up a new team member - Iron Man.
There have been murmurings that Iron Man will have a cameo appearance in the Guardians of the Galaxy movie itself - but another possibility is that if the movie does well, Tony could spend Iron Man 4 hanging out in space with a few of the GotG guys.
It's a long shot, but then so was the Guardians of the Galaxy getting a movie in the first place.
If S.H.I.E.L.D. needs a director, would Tony Stark be a decent candidate?
Now, SPOILER alert going into this. S.H.I.E.L.D. is gone, at least for now. But it will be back - odds are, in Captain America 3. When it does return, though, if Nick Fury is busy elsewhere, then the comics have a solution.
For a while there, Tony Stark was totally in charge of S.H.I.E.L.D.
Which doesn't really go so well in the comics, but that doesn't mean it wouldn't offer up an interesting twist to the current Marvel Cinematic Universe. There's obviously a lot of support for S.H.I.E.L.D. related plots - especially post Captain America: The Winter Soldier, and it would open up a much more Agent Coulson/Black Widow/Maria Hill related storyline than anything else could.
Gwyneth Paltrow too expensive to bring back?
Cobie Smulders has got it covered.
What if there's some sort of war, though? Some sort of civil war? Where will that leave Iron Man?
Ask around at Comic-Con what you think the plot of Avengers 3 should be, and Civil War won't be far from your ears. One of the most shocking - and arguably the era-defining - Marvel comics storylines of the last ten years, Civil War and its aftermath pitted Earth's Mightiest Heroes against one another - in large part as a result of Iron Man not being all that big on civil liberties.
Y'now, those things that Captain America: The Winter Soldier was pretty much entirely about.
It was an epic, Marvel-universe spanning fight, one that saw Captain America and Iron Man find themselves on opposite sides of a fundamental divide - the conflict between freedom and security.
Again, that thing the Marvel Cinematic Universe is already all about.
Remember how the first Avengers movie went to all that effort to have the heroes fight each other at the slightest opportunity?
Well, this would be a whole movie of that - with the ridiculous number of Marvel movie heroes we would have by that point duking it out over two and a half hours, about things that fundamentally matter.
And you know what comes out of that - assuming that Captain America and the American Way come out on top? Iron Man 4: Pariah. Think Iron Man 3 - only Tony is being hunted down by whichever heroes and villains feel like getting out of bed that week.
Make the two movies a crossover type deal - just like they do in the comics - and you've got yourself quite an event.
If Robert Downey Jr isn't coming back, don't worry. The Crossing has you covered.
Lets be honest. There's a decent chance that Downey Jr isn't coming back for Iron Man 4 - whatever Shane Black might say. He might be way too expensive, or he might just not feel like doing it. Seeing as he's now about as rich as Tony Stark from all the Marvel movie money, that isn't out of the realms of possibility.
If that happens, though, how can Marvel keep the franchise going without awkwardly recasting a character - knowing that whoever replaces Downey Jr will be booed by default?
Once again the comics have an answer.
In The Crossing, a storyline that was later ret-conned more or less out of existence, Tony Stark turns out to have been an inadvertent, brainwashed traitor. To stop him, the Avengers go back in time, and bring back a nineteen year old Tony Stark. Traitor Tony then dies the traditional noble death, leading his teenage self to take over.
Now, that isn't going to happen - not least because almost nobody has ever liked that storyline. But lets say Avengers 3 is going to end with Stark losing some sort of elaborate civil war. Give him a quick mind control alibi - setting up a new villain in the process - then have him die nobly, and hey presto, you have a perfect tragic ending to the trilogy.
And then you can have him come back from the dead.
As a clone, maybe. A strangely different looking clone. A clone almost teenage in appearance.
Someone, perhaps, who has previous experience replacing legendary superhero figures.
Iron Man Returns, anyone?