An unfortunate translation is any that uses “world” for “age.” In one sense, we could refer to people of a certain period as “their world.” Still, this would not carry the idea of the planet earth (kosmos) on which humankind lives, but a certain age or era. The Greek word used does not have anything to do with the end of planet earth. “King James Only” advocates can have their 1611 translation, if you insist. I will prefer the Greek text and it consistently uses “aion” (age), not the kosmos.
The terms used to describe this period pulls the coming (parousia) of the Lord and the Holy Spirit in the last days together with the end of the Jewish age or “world order.” The earthly realm of physicality that described the grandeur of a people whose God was Jehovah was a shadow of spiritual realities. Whether we refer to those days as “the end of the age” or “the last days,” they refer to that same climactic time of fulfillment.
The specific phrase, “end of the age” is found six times in the New Testament. Matthew, who is noted for having written to a Jewish audience, mentions it five out of the six times (Matthew 13:39, 40, 49; 24:3; 28:20). The only other time is found in the book of Hebrews (9:26).
A well-known passage that is misapplied to refer to our age is Matthew 28:20. It reads, “…teaching them to observe all that I commanded you; and lo, I am with you always, even to the end of the age?” Obviously, there is sense in which we could say that Jesus is with us today, but not in the context of this passage. The apostles were commissioned to go into the world to preach the gospel. Like Moses and the prophets that followed him, some lacked the courage and refused the call to go. They were all given the same message of confidence that they would not be alone. God would be with them. For example, Luke 12:11-12 is an example of Jesus being with the. Jesus says, “When they bring you before the synagogues and the rulers and the authorities, do not worry about how or what you are to speak in your defense, or what you are to say; for the Holy Spirit will teach you in that very hour what you ought to say.” Matthew 28:20 was not written to us who are centuries removed from the “end of the age.” It was written to the first century saints who were anxiously awaiting the Lord’s return. In the midst of persecutions and trials that will come upon the preaching of the gospel, Jesus assures them that He will be with them to the end of the age.
1 Cor. 10:11 gives the plural, “ends of the ages” in the following context that addresses the value of the ages. It reads, “Now these things happened to them as an example, and they were written for our instruction, upon whom the ends of the ages have come.” As to the plural, many establishments and traditions ended and in each age that ended, the example of sin and God’s just recompense of reward provided the reason for the cross and the kingdom of Christ. The ultimate fulfillment of God’s plan was the end of the Jewish era, but both Noah’s day and the Mosaic era pointed to the new creation of the called out people of God. While the first age was followed by a second, it also pointed to that day. They are placed together so that even the vindication of the blood of Abel would be take place in the last days.
The Hebrews writer uses the phrase “end of the age(s) interchangeably with the “last days.” Chapter 1 starts with a reference to God speaking to those in the last days through his Son, while Hebrews 9:26 informs us that Jesus was manifested to put away sin by the sacrifice of himself at the “end of the age(s) (cf. Matthew 24:3).” All three of these texts (Heb. 9:26, Matthew 24:3, and 1 Cor. 10:11) do not directly describe a literal 24 hour period that ended, but points to “the consummation of the age.” In other words, God’s redemptive plan was the “end” or “completion of the age.” The end of the law pointed to the completion of its purpose. Therefore, the offering of His body was the consummation of the plan of God through all ages (plural). Mosaic age was not intended to last forever but had the purpose of introducing the grand entrance of the Christ (cf. Gal. 3:15-29). Certainly, the strong inference is that once it had completed its purpose in that age, it ushered in the new and living way (a new age).