Is forever / everlasting until the end of time or for a period or is there a conflict between the two passages?
Isaiah 32:14 For the palace will be forsaken, the busy city abandoned. The hill and the watchtower will become caves forever (‘ō-w-lām)—the delight of wild donkeys and a pasture for flocks—
15 until the Spirit is poured out upon us from on high. Then the desert will be an orchard, and the orchard will seem like a forest.
The meaning of the Hebrew word עוֹלָם (olam) is much debated - see its many uses and how it is translated here >> https://biblehub.com/hebrew/5769.htm
There are many instances where it truly means forever without limit and other times where it means for a long period and other where it means for a period of time without interruption.
Isa 32:14 is a perfect example of the last meaning - for a period of time without interruption, or with conditions. The word is frequent in prophet writings about the future.
Isa 32:9-20 is a prophecy about destruction of Jerusalem and the desolation of the city which (historically speaking) lasted from about 586 BC to about 537 BC - about 40 years. During this period of desolation, Jerusalem was inhabited by wild animals, etc. It took even longer to be replanted with lush harvests.
The use of the preposition עַד־ (until, V15)) is the clue to understanding the meaning in V14. The Cambridge Commentary says the same thing:
The phrase for ever must be understood in a relative sense, being restricted by the “until” of Isaiah 32:15.
The Pulpit commentary reaches a similar conclusion:
For ever. This expression must not be pressed. Hyperbole is a recognized feature of poetry written under strong excitement.
