The earliest Gospel is Mark, written about 70 during the Jewish upheaval that saw the Second Temple destroyed. Mark saw the destruction as indicating the end was imminent. The Matthew Gospel was written about 10 years later, or so. By the time Matthew wrote, he/they added and amended Mark to explain why there had been a delay. The Matthew writers were not happy with Mark's so they added to it and amended it.
By the time "Luke" got around to collecting his thoughts together, another decade or three had passed. Luke, as with Matthew, included material from Mark as well as other written and oral material.
These people were all talking to their own people about their own time. They were not talking to any later generation. They were trying to explain why the expected Coming had not taken place, hence their changing language.
Other Christian groups, known today as Gnostics, laughed at discomfort of the Parousia expectations by the Pauline Christians. Hence the language of 2 Peter, which was written later again, about 120 CE.
Doug