And then you could ask, in what way has it cooled off? Or are we now applying "the greater number" to the number of Jehovah's witnesses, which is stagnant and a 1000+/1 minority in the world?
Most of the references to this verse in the past 30 years highlight the "increase in lawlessness". Where they talk about love cooling off it's related, as the context suggests, to the general population becoming more selfish and decreasing in their love for God.
The only place it gets close to relating it to Witnesses is in the Insight book under "Love":
One’s Love Can Cool Off. Jesus Christ, in telling his disciples of the things ahead, indicated that the love (a·gaʹpe) of many who professed belief in God would cool off. (Mt 24:3, 12) The apostle Paul said that, as a feature of the critical times to come, men would become “lovers of money.” (2Ti 3:1, 2) It is evident, therefore, that a person can lose sight of right principles and that the proper love he once had can fade away. This emphasizes the importance of constant exercise and development of love by meditation on God’s Word and by molding one’s life according to His principles.—Eph 4:15, 22-24.The neat trick is that simply through osmosis this idea that this scripture refers to Witnesses gets spread. The phrase the "love of the greater number will cool off" is repeated in conversation and without context yet the context gives a reason for this love cooling off - the increase in lawlessness. When taken in this context it's hard to see a direct prophetic link to the malaise of the Witnesses yet the rank and file see it with no significant and direct discussion by the WTS - in fact the opposite is true.
It's cognitive dissonance. Plain and simple.