Filming is finally set to start on The Expendables 4 this summer. The original Expendables started life as a gritty action movie about veteran mercenaries, but when writer/director Sylvester Stallone started adding action icons like Jet Li and Dolph Lundgren to the cast, the project morphed into an homage to classic '80s action movies. The resulting film was a fun but flawed adventure, and a big financial success.

The Expendables 2 added the likes of Jean-Claude Van Damme and Chuck Norris, and got Arnold Schwarzenegger and Bruce Willis in on the action following their brief cameos in the original. The film was an even bigger success, but 2014's The Expendables 3 performed well below expectations. The film was shot as a PG-13, removing any trace of bloodshed or bad language, and considering the old school appeal of the previous movies, this was considered a mistake. The film also added a bunch of young, uninteresting mercenaries to the line-up in an attempt to appeal to a younger audience.

Related: Stallone Teases Expendables 4 Production

Due to the disappointing performance of The Expendables 3, and Stallone and Schwarzenegger ruling out a return, it appeared the franchise had run its course. Then in January 2018, Stallone started hinting the movie was back on, and now in an interview with The Arnold Fans, co-star Randy Couture confirmed the next sequel is aiming for an August start date for filming:

I’m excited about Expendables 4. Right now, we’re scheduled to start filming in August and hopefully we’re able to stay on schedule. It sounds like we’re coming back to Bulgaria, which is exciting. I’ve spend a lot of time in Sofia and Varna and I’m excited to come back. I love the people (there), I love the food and I’m excited to come back.

The Expendables franchise has appealed to fans of old-fashioned, R-rated movies that went out of style when comic book movies started to become popular. The focus for a long time was on movies with lots of CGI and green screen effects, while more grounded action fare started going to straight to DVD. With The Expendables, Stallone was able to unite a lot of the major stars of that era for a glory lap, and while the film's themselves have never been critical darlings, there's something charmingly retro about them.

Outside of Stallone and Couture, no one is confirmed to be returning for The Expendables 4. Regulars like Jason Statham and Dolph Lundgren seem like a given, but previous co-stars like Harrison Ford, Wesley Snipes and Jet Li are more of a question mark. Bruce Willis was due to reprise his role in The Expendables 3, but had a public falling out with Stallone when he demanded a $4 million fee for 4 days filming; he was replaced with Harrison Ford as a new character instead.

Part of the fun of The Expendables franchise is seeing the latest action star they can rope in, but the pool of iconic actors is feeling a little shallow now. Dwayne Johnson, Sigourney Weaver, Nic Cage and Donnie Yen regularly pop up on fan wish lists, so part 4 will need to provide a couple of amazing newcomers. There was also talk of an Expendables television series a few years ago, but nothing has been heard in the intervening years.

More: Expendables Event TV Series Being Developed By Fox

There's no release date for The Expendables 4, but we'll update you as more information arrives.

Source: The Arnold Fans