Not having existed yet is spoken of as not yet having come. Alternate translation: "the other has not yet become king; when he becomes king" (See: [[rc://en/ta/man/jit/figs-metaphor]])
The angel speaks of someone continuing to be king as if he were remaining in a place. Alternate translation: "he can be king only for a little while" (See: [[rc://en/ta/man/jit/figs-metaphor]])