God shakes heaven and earth to remove the old order so the unshakable Kingdom remains.
Haggai 2:6 is applied in Hebrews 12:26–27 to the removal of things that are shaken — the Old Covenant administration.
In Acts 4:31 the place of prayer is shaken as the Spirit fills the church again — a sign of covenantal upheaval.
The Kingdom that remains is the New Covenant reality. The shaking ends the Temple age, not the physical creation.