I am enjoying your articles but must say you have not read enough about premillenialism. You may have an author or two as your favorites to pick on, but you must know that even among premillenialists there is not 100% agreement on every passage, and indeed, there is no doubt some real zingers in some details of beliefs.
The key issue is whether there will be a literal earthly kingdom in the future. The best (IMHO of course) position within the premillenial camp is that the coming earthly kingdom is the fulfillment of the kindgom referenced in Daniel and 2 Samuel (Davidic kingdom promise). Yes, there will be a new heaven and earth some day, and when that precisely happens I do not know ... but when the texts says "eternal kingdom" I am bound to conclude that that kingdom will not be destroyed because of a new earth. My family is not destroyed because I move from an old house to a new house.
The passage you highlighted talks to this critical issue.
3. Where Christ dwells, there He rules. Hence "the kingdom of God is within you" (also rendered "in your midst" or "among.")
This passage is the famous "Kingdom in the heart" passage that many people use to claim no earthly kingdom. But as you estutely point out, the greek is a little ambiguous here with the translation of the work 'within'. It can also mean 'in your midst' or 'among' you.
This is very important. When Jesus was talking about a kingdom, what kind of kingdom were the Jews expecting? ... They were expecting an earthly kindgom which fulfilled the Davidic covenant, which is the eternal kingdom mentioned in Daniel. And to the Jewish mind, there was absolutely no difference between the King ... and the Kingdom.
"You O King ... are that head of gold. And after you shall arise another kingdom ... " Daniel 2
Jesus was saying the kingdom of heaven is among you ... in the sense that the king is here right now in your midst. But the complete fulfillment of the promise of the kingdom will not take place until his 2nd coming.
When John the Baptist declared in Matt. "repent, for the kingdom is at hand" ... there is only one context where they could have understood what kind of kingdom John was talking about. The long awaited fulfillment of the Davidic covenant.
If you look at all other gospel passages that reference the kingdom of God, you cannot get away from a literal earthly fulfillment of the Davidic covenant, and the fulfillment of Daniels prophecies.
That there will be an eternal kingdom, and a new heaven and new earth is not in question.
The article raises the question of hermenuetics, whereby the premillinialists interprets 1000 years in one passage as literal and another as symbolic, and there are two separate resurrections divided by the 1000 years when Jesus plainly says that the day is coming when all will come out of the grave for judgment.