The Watchtower does not believe in "the end of the world."
Only they do. This is what they were teaching in the lead-up to 1975 and continue to teach today:
“The world is passing away and so is its desire,” says 1 John 2:17. What is that “world”? How and when will it pass away?
What is the “world” that will end?
WHAT THE BIBLE SAYS
Because the world in question has ‘desires’ that merit God’s disapproval, it is obviously not the literal earth. Rather, it is the world of mankind who disregard God, making themselves his enemy. (James 4:4) The people who make up that world “will undergo the judicial punishment of everlasting destruction.” (2 Thessalonians 1:7-9) On the other hand, people who remain “no part of the world,” in obedience to Jesus Christ, have the prospect of everlasting life.—John 15:19.
Indeed, 1 John 2:17 concludes: “The one who does the will of God remains forever.” Yes, that one has the prospect of everlasting life right here on earth, as stated at Psalm 37:29: “The righteous will possess the earth, and they will live forever on it.”
Search also, site:jw.org world ends