I do think there has to be a “day of the Lord” as in some sort of consummation or birth. Paul talks about this in Romans 8 – how the whole creation groans together (including us Christ followers) in birth pangs until the present time, longing for the revelation of the sons of God (that is, the huios or mature offspring of the Father), and for the redemption of our bodies – how the creation will partake of the blessedness of these huios of God and will be set free from the bondage of corruption to which it was subjected in hope – so that the whole creation could reach a state of harmony and perfection, maturity, liberty, etc.
We see this theme of birth pangs, of a marriage celebration, of a general resurrection and judgment – all through scripture. When a woman is pregnant, it seems to her she will always be pregnant. The birth, though she may know it is imminent, may seem to be a thing that never will come. She has a general idea of a time frame (which we don’t really, for the birth of the resurrected world), but she doesn’t know exactly when it will come. In the Hebrew marriage, I’ve read that the situation was similar. The bridegroom would come to collect his bride when his father said the place he was preparing for his betrothed was completed. Neither the groom nor the bride would know specifically when this would happen – only that the waiting, the separate period, would typically last for about a year. The bride and her maidens must be ready at all times because the groom would come unannounced, typically at night, and take them to celebrate the marriage feast at his father’s house (or “insula” where the groom would have prepared the new suite for his bride and himself.)
Even physical death is usually like this. When my father was sick with his last illness, it was an indefinite thing. I knew it would take him, and soon, but as he languished day after day, it was hard to think of his death as a definite, imminent thing. And then one day he was gone. I think the day of the Lord is probably similar. We know from scripture that this world, in its present corruption, will not go on forever and ever – yet it seems that it will. It will end/transition when the time comes, and only the Father knows that time for certain.
Yes, there will doubtless be people who have yet to repent when that Day comes. I don’t think the final consummation can come though, until everyone DOES repent. Looking at the final chapters of Revelation (though it is symbolic, it is symbolic of SOMETHING, and probably many things), I see the Day of the Lord having come with its judgment and its celebration of the Marriage of the Lamb, and yet some left out in the dark, outside the Holy City. But then I see God becoming All in All (in Ephesians I think?) and every knee in heaven, on the earth, and under the earth confessing Jesus as Lord to the glory of the Father. So, some do seem to miss the festivities (as Jesus repeatedly warns His listeners), but are later drawn into the joyous Kingdom of God.
I have a kind of “wider vision” or at least an inkling of a suspicion of things to come though, and if it’s even passingly correct, I’m not sure how it fits into this idea of a final consummation. I really do see God continuing to develop the less conscious animals to a state of perfection and maturity too, and maybe even other life forms – maybe even the universe itself. It seems to me to fit. If God created US via evolution, why make that process end? Why stop at this universe (which perhaps isn’t even the first, or the only), since we know that God is infinite? If that’s the case, perhaps there will in time be many consummations, many celebrations, many ages. It’s all too vast for me to take in or make a systematic description of, but it seems right to me. I’m excited to see things closer one day, and to understand better things that now I only see as dim, misty shapes of shadowy possibilities.