Marvel fans desperate to see Robert Downey, Jr. in "Iron Man 4" have been put on ice lately. There have been zero updates about the sequel since the last film, "Iron Man 3," was released in 2013. Since then, all we've gotten is a few moments of Downey, Jr. waffling back and forth- saying the next film's confirmed, then admitting it might not be.

But the "Iron Man" star and Marvel lynchpin made a big announcement on Twitter recently. The actor posted a new poster of himself from the upcoming "Avengers: Age of Ultron." The poster (seen above) shows Iron Man, helmet off, striking a pose as an army of Ultron minions comes swarming after him.

The poster's cool, but the poster's not the real news here. Because with it, Downey, Jr. tweeted something very mysterious:

"You've been good so here's a new #IronMan poster from @Avengers. & on the DL, big announcement in 8 days... #getexcited"

The image was posted on February 25, so 8 days from that would be March 5. And what could the surprise be? IndiaGlitz has a few opinions on the matter, and they're suggesting it may in fact be an official announcement on "Iron Man 4." Of course, they also note that the film might be a scheduling nightmare- Marvel's already got every film locked down until 2019, and they've also just had to rearrange everything to fit in a new "Spider-Man" film. It's hard to imagine they'd change things again, and so soon.

However, HitFix has the same idea- this might be an "Iron Man 4" announcement. If so, this would take the Marvel world by storm- fans have long wondered what Downey, Jr. is going to do once his contract is up, and another "Iron Man" film would keep the fans happy, and not worried that their favorite hero was leaving the franchise.

Only 8 more days to go... we'll find out next week!