Luke 12:38 And if he shall come in the second watch, or come in the third watch, and find them so, blessed are those servants.
The Greek word there is "kai",
which does not mean "or". The word "kai" should be translated as
"AND" (meaning in addition to something) or "
EVEN" (meaning namely, or specifically).
The parable was intended to include TWO comings of the Lord
"in the second AND (kai) the third watch" - not just one coming. The lord in the parable was returning from the marriage feasts (PLURAL in the Greek). The Apostles understood it this way also, which is why they asked the Lord "speakest thou this parable unto US or even unto ALL? Christ's disciples would experience the second coming in their first-century time frame (the second watch), but there would be one more
additional coming beyond that one (in the third watch). For those servants who would be found faithfully watching on BOTH those occasions, they would all be blessed.
Jesus will return to burn up the entire surface of the earth with fire just like the entire surface of the earth was flooded with water in Noah's day.
"The earth abideth
forever". God has no intention of incinerating this entire planet in the future.
I agree that the final coming of Christ in our future will rid the planet of all remaining human evil at that time. But that doesn't apply to the planet itself. The dirt under our feet is
not evil. Neither is it in need of being burned up to purify it. If Peter had wanted to say that the entire globe would be incinerated in 2 Peter 3:10-13, he would have used the word "kosmos" or "oikoumene" in that text - NOT "tes ges", which scripture usually applies specifically to the "land" of Israel - the promised land. "The earth and the works that are therein" (such as the Jerusalem temple)
were burned up back in AD 70, which manifested Isaiah 65's "new heavens and new earth". Certain conditions that had existed in the heavens and the earth
were changed back in AD 70 at "the ends of the ages" which Paul said had come upon them at
that time (1 Cor. 10:11- written around AD 57).
...when the old covenant actually ended and was made obsolete, which was at the cross.
I'd pinpoint this transition to the New Covenant just a bit later on with its being launched at Christ's resurrection-day ascension and the "change in the priesthood" - but I agree that the official transition to the New Covenant did
not begin in AD 70. God was merely "taking out the trash" in the AD 70 period by burning up all the features of a dead, decaying physical temple system.