What version are you getting huios translated "children"? That's incorrect, and changes the meaning for the passage considerably. The Greek huios is "son" or, in this case, plural "sons." This word is used very specifically throughout the New Testament, as it was a legal term that was equally applied to a natural son or an adopted son. We are adopted in Christ, through faith by grace that His shed blood is sufficient sacrifice for forgiveness of our sin.
Also, the word is not "world", but "age", the Greek aion. Though it usually denotes a specific timeline, it also can mean an unbroken age, perpetuity of time. I believe that latter meaning is appropriate here, because that would indicate that the heart of man not turned from stone to flesh by the love of Christ is the same always and forever, whether living in the time of Moses or in the time of our great-grandsons.
In that sense, the "sons of this age" are the same as they were when Jesus spoke the words in the first century. They are the condemned, the unbelievers, those who prefer darkness to light because in the light their deeds are seen and known to be evil. The message of God is the same yesterday, today and forever. "Love Me, love one another." But we must love Him specifically through Christ, which is what the message always has been, from the time Abraham believed "and it was reckoned to him as righteousness." Abraham didn't know the specifics of the promise, but he still knew from Whom the promise came, which was all he needed to know.