I just read this line "Discipleship can easily be forgotten when churches focus on mission."
That sentence makes my head hurt. According to the Great Commission, mission = making disciples. If you've even begun to think of "mission" and "discipleship" as two separate activities, then it's time to back-track.
There is only one valid mission; it's to teach the nations obedience to Jesus. To do what Adam failed to do: fill the earth with God's glory through an obedient human race. Whatever stage those you concentrate upon (whether as a pastor amongst an established flock, or pioneer evangelist in an unreached area, or whether serving God in various ministries intertwined with a secular calling), there's only one thing you're doing: enabling people by word and prayer to follow Christ. Mission and discipleship are one. Any other approach is reducing the Christian life to a list of activities - bit of discipleship here, bit of mission there. But God's creation and his redemption thereof are not meant to be atomised in that fashion. If you forget discipleship when you focus on mission, then you've forgotten the big picture of what the Christ-given task is for the human race.