What does Luke 22:30 mean?

Considering the context of this chapter, this night, and the day to come, this is an extraordinary promise. It is the Passover meal. Jesus and His disciples are having a private celebration. Jesus has spoken of the new covenant and the method by which He will usher it in. He will pay for the sins of the world and reconcile people with God through giving His body and His blood.

But this night, Judas has gone to betray Jesus (Luke 22:3–6). The disciples argue about who is the greatest (Luke 22:24). Then they'll sleep when they should be praying and run when they should remain with Jesus (Luke 22:39–46; Mark 14:50). And Peter will deny Him three times (Luke 22:54–62).

Despite the disciples' inconstancy, Jesus identifies them as "those who have stayed with me in my trials" (Luke 22:28). Despite their inappropriate grasping for power, He promises them a kingdom, a place at His royal table, and thrones on which to judge the tribes of Israel. In twenty-four hours, when Jesus is in a tomb and the disciples are in hiding, they will find this exceedingly difficult to believe.

It will happen, but the exact details and timing are God's responsibility. Earlier, when James and John's mother asked Jesus to give her sons special places in His kingdom, Jesus said, "To sit at my right hand and at my left is not mine to grant, but it is for those for whom it has been prepared by my Father" (Matthew 20:23). Moments before Jesus returns to heaven, the disciples will ask, "Lord, will you at this time restore the kingdom to Israel?" (Acts 1:6). Jesus responds, "It is not for you to know times or seasons that the Father has fixed by his own authority" (Acts 1:7).

The disciples learn that they can't assume authority by subjecting people to their power: they don't have any power. But they will lead when God gives them power and authority.