The Watchtower Study Edition, August 2015, "Keep In Expectation!" Article:
Paragraph 3: "After looking forward to the end of this system for what may seem to be a long time, however, some may wonder, ‘Do we still have sound reasons to keep in expectation?’ Let us see."
Paragraph 5: "Jesus did not say how long that period of time would go on before the end arrived"
Paragraph 6: "We might ask: Could not 'the conclusion of the system of things' refer to a future time when world conditions will become even worse? The Bible does indicate that wickedness will greatly increase 'in the last days.' (2 Tim. 3:1, 13; Matt. 24:21; Rev. 12:12) So we can expect that world conditions, bad as they are now, will continue to decline."
Paragraph 10: "Many of us have been keeping awake spiritually for decades. However, let us not allow the passing of time to weaken our resolve to keep in expectation."
Paragraph 11: "He said: 'Keep on the watch.' So a long wait would not justify mentally postponing the end or totally dismissing their expectations."
Paragraph 14: "We will surely be thankful that God, who ‘has placed times and seasons in his own jurisdiction,’ exhorted us to live with an awareness that ‘the end of all things had drawn close.’—Acts 1:7; 1 Pet. 4:7."
This ties in with the "Newest Light" from the 2015 Insight Book regarding the "generation":
"So his comment about “this generation” logically had an application down to 70 C.E. However, he was also using the word “generation” with reference to humans whose lives would in some way be associated with the foretold events during his presence."