Disney will be shutting down both Marvel: Avengers Alliance and Marvel: Avengers Alliance 2.
In a statement on the game's FAQ, Disney states that "we feel it’s best to focus our energy and resources into making new games and digital experiences for our fans and community."
IAPs in both games have been deactivated, and both games will be inaccessible from 30 September 2016.
Marvel: Avengers Alliance 2 launched on 30 March 2016, so the game will have run for just six months before its closure.
It's a shame, but not particularly surprising.
Indeed, the game failed to hold its own against the plethora of other Marvel games available when it launched, and lacked an autoplay function which would've helped with long-term retention.