Back in 2012, Yager Development released a shooter that was fairly well received by critics and fans. Since then, there's been no talk of a sequel for Spec Ops: The Line and it looks like there might never be one.
According to Spec Ops: The Line's lead writer Walt Williams, the game's development process was so painful, the devs would "eat broken glass" before making another. In addition that, the game simply didn't sell enough copies to elicit a sequel.
Because it was a brutal, painful development & everyone who worked on it would eat broken glass before making another. Also it didn't sell.
— The Walting Dead (@waltdwilliams) October 3, 2017
That's it. There's the nail in the coffin for Spec Ops: The Line 2.