Where does it say that OT holy days had to be "fulfilled"? Isn't it clear that term 'earth' can mean the local land/estate rather than the entire planet called "Earth"? How does 1 + 3 = 5? The kingdom of is current it is active right now and has been even since the ascension followed by the conferring of a kingdom to Jesus Christ (Ephesians 1). It seems that charlatanous counterfeits have (for thousands of years) set out to deceive people into believing otherwise or even to become part of their counterfeit systems.
I would tend to suspect that a 'desert' would be where there would be spiritual dryness rather than a physical desert. A lot of folks seem to forget Isaiah was before the Babylonian Captivity (~745-685BC).
Its challenging at the least to see much merit in any paradigm that glosses over the significance of Ephesians 1 and the significance of Acts 2 (Pentecost day) or in one that effective supposes Isaiah to have come after the Babylonian Captivity period. Not saying that the one doug555 proposes. The word "america" is already known to have the possible (root) meaning of "kingdom of heaven" (himmelreich+a). In the sense of a local 'earth' meaning, America is not physically a part of the local 'earth' from the perspective of Ancient Sumeria or Palestine--neither were the British Isles which might be why they could become save havens (heavens).