Even though the kingdom of God has come in Christ (Matt 3:2, 4:17, 12:28), and Christ has been raised to God's right hand where he has authority over all, there seems to be something not right, not "yet" so to speak.
"Yet some biblical expectations for the last days and the kingdom are still unfulfilled. The bodily resurrection of the just and the unjust has not taken place. The return of Christ and the final judgment remain future. The saints pray, "Thy kingdom come". That prayer assumes that the coming of the kingdom is future to some extent, though the prayer contains petitions for the near future, not only for the ultimate consummation." - Frame, ST, p89.
And this relates to what he spoke of earlier: the dynamic and dramatic nature of the present kingdom of God. There will be real ups and downs. There are real promises and there are real unfulfilled manifestations of those promises, with real and hard consequences of those unfulfilled promises. And yet, there is a real change in the universe because we live in the "age to come." Rulers have been put down and no longer have the kind of control they did.
The leaven is spreading. The story is unfolding.