And it shall come to pass in the last days, that the mountain of the LORD's house shall be established in the top of the mountains…
The description of "the last days" — which in the Hebrew begins, "And it hath come to pass...the mountain of Jehovah's house shall be established," etc. — is an instance of the use of the perfect tense to express the certain future. Its explanation seems to be that the structure of such a passage as that before us is imaginative, not logical — a picture, not a statement. The speaker completely projects himself into "the last days"; he is there, he finds them come; he looks about him to see what is actually going on, and sees that the mountain of Jehovah's house is about to be — still in process of being — established at the head of the mountains; he looks again, and the nations have already arrived at the place prepared for them, yet so freshly that they are still calling one another on; and as they come up they find that the King they seek is already there, and has effected some of His judgments and decisions before they arrive for their, turn.
(Sir E. Strachey, Bart.)
Parallel VersesKJV: And it shall come to pass in the last days, that the mountain of the LORD'S house shall be established in the top of the mountains, and shall be exalted above the hills; and all nations shall flow unto it.