According to my view, in many cases where there is a "farther mountain" peak in view, it is only as the "vehicle" (i.e. the imagery) through which the prophet describes the "tenor" (i.e. the referent) of his prophecy about the near future. In other words, the prophets sometimes used eschatological language consciously as a metaphorical lens when referring to something else - the common usage of the "day of the Lord" throughout the OT the best example of this phenomenon. We can tell from the first occurrence of the phrase, in Amos 5:18-20, that it had already carried a popular meaning within Israel, since the prophet uses it polemically. Amos' contemporaries longed for the day of the Lord as the climactic moment in Israel's history, the time when YHWH would act on their behalf and bring victory over their enemies. But because of their unfaithfulness, Amos turns that expectation around and speaks of the "day of the Lord" as a time of judgment for Israel and not victory. In other words, he holds up Israel's eschatological expectation of judgment against their enemies
as a lens for them to understand God's present judgment against them
. An yet, because Amos does not see God's judgment against Israel as the final word, but still affirms a redemptive hope beyond that judgment, we know that he did not truly think of that judgment as the
day of the Lord in the ultimate and established sense of the phrase. Hence, he uses it as an eschatological metaphor.
I think similar language is used throughout the prophets when referring to immediate socio-political events. I wouldn't suggest this as a holistic hypothesis for all
prophetic language, but rather as an explanation for some
instances of prophetic language on a strictly case-by-case basis. If I could put my view in a series of propositions, it would look something like this:
1. The biblical writers believed that human history was moving towards a goal, a time when all things would be made right, a time when sin would be dealt with, when evil would be judged, and when God's people would be redeemed and vindicated.
2. The biblical writers often used end-of-the-world language to refer to this climactic expectation, but they did not believe in a literal end of the material universe. Rather, in contrast with later Greek thought, their hope was very concrete and this-worldly. At the very least, then, such language is hyperbolic.
3. Some biblical writers also used this type of language metaphorically to refer to that which they knew well was not the final or climatic goal of history, because they perceived typological associations between the present referent and the final goal and thereby invested the former with the meaning of the latter.
4. It is appropriate then to speak in these instances of prophetic language carrying an eschatological excess beyond its primary referent, as the imagery itself evokes the final goal which is embedded in the Judeo-Christian expectation.
I think this account answers for a regular phenomenon in biblical prophecy that is often explained on a popular level through the literalist category of "dual fulfillment" - but I think it has the advantage of being much more sensitive to the way biblical language and imagery actually works.