After discharge he will be free to rejoin Super Junior again.
Kangin joined the army shortly after his scandal broke in September and October 2009, then joining the army in July 2010. During the time away from Super Junior they released, ‘Bonamana‘ and ’Mr. Simple‘.
Super Junior are are currently on their “Super Show 4” world tour. Kangin will most likely be joining them for their next project after the tour.