When you get a Gospel like that we had today about sun and moon no longer shining and the stars falling from the heavens then you know that what has been written on has very little to do with "when". The end is not the conclusion of one chapter, that allows us to anticipate succeeding chapters. It is the absolute end -- that responds to the question: What has it been all about. That Jesus makes clear that when it is to happen is known neither to angels, nor to him but only to the Father is his way of saying that pursuing that query is idle. What counts is that there is a plan.
Eschatologies engage, because we all have a sense of our fragility. That partly explains why most of the time we think of catastrophic and cataclysmic ends -- like 2012 that I still have to watch! We know, for all the pomp and glitter with which we make pretensions at greatness, that our grip on meaning is tenuous.
The coming of the Son of Man in glory is the promise of meaning, eternal validity, vindication. We will be gathered -- not scattered, for annihilation and meaninglessness are really scattering!
It would do us well to think more often of the absolute end as far as we are able to, especially because we are so often taken up in the petty ends we set for ourselves (sometimes great ends too!) and think the world of them. It is good to be reminded that the world is to be shaken up so that we can start thinking beyond thought (for thought has become captive of what we can colonize.)