Arma 4 isn't in development, but Arma 3 won't be the end of the series

Arma 3 won't be the last we'll play of the milsim series, but it's too early to tell what form a hypothetical Arma 4 would take, says developer Bohemia Interactive.
Speaking to PC Gamer via email, brand and PR manager Korneel van 't Land said that the studio's goal right now is "to keep Arma 3 fresh and exciting for at least several more years" as it balances development on several other projects. Bohemia says it would like to continue the series beyond Arma 3, but doesn't have any plans to share about a sequel right now.

Why is the idea of an Arma 4 being discussed? Last Friday, a Slovakian journalist who was visiting the Czech studio tweeted falsely that the project existed. "Our editor is in Bohemia Interactive today. I can now say that Arma 4 is officially confirmed #Arma4 #Arma," wrote Lukas Kanik, who works for games outlet CentrumHer.
The tweet was deleted the same day, but not before Reddit's popular /r/games forum picked up the rumor and ran with it. "ARMA 4 in development, editors are visiting Bohemia Interactive," read a 233-comment thread, where redditors speculated enthusiastically about features, settings, and an Arma 4 release date.
I reached out to Bohemia to find out whether there was any truth to this. "We were hosting something called 'Arma 3 Creator Bootcamp' last week, for which we invited potential third-party DLC creators for Arma 3 to provide them with some guidelines and help kick off the development of their projects," van 't Land explained. "We figured that we’d also invite a few local media outlets as well."
The final day of #Arma3 Creator Bootcamp is ongoing, and the participants are currently outside for a ride with @bohemiatank!
Game developers rarely say anything about unannounced sequels, so as confirmation goes, Bohemia's explanation is generous by industry standards. Arma 3 released in 2013, four years after its predecessor Arma 2 in 2009, so fans could be forgiven for thinking that another entry in the series might be around the corner.
This week we'll be hosting an #Arma3 Creator Bootcamp at our Mnisek studio to help kick-off the development of third-party DLC. It's an opportunity for us to meet with, and provide guidance to, the 18 invited participants who sent us a promising pitch. Stay tuned for photos!
In addition to its work on a new engine, Bohemia continues development of Ylands, its Xbox One shooter Vigor, and DayZ 1.0, which will hit this year.
