So, is this all still future, or has it been fulfilled? I think that it’s important to note that Jerusalem and the temple were destroyed in 70 AD. It was a time of immense tragedy, captured by Josephus in his writings:
“(404) But when they went in numbers into the lanes of the city, with their swords drawn, they slew those whom they overtook, without mercy, and set fire to the houses wither the Jews were fled, and burnt every soul in them, and laid waste a great many of the rest; (405) and when they were come to the houses to plunder them, they found in them entire families of dead men, and the upper rooms full of dead corpses, that is of such as died by the famine; they then stood in a horror at this sight, and went out without touching anything. (406) But although they had this commiseration for such as were destroyed in that manner, yet had they not the same for those that were still alive, but they ran every one through whom they met with, and obstructed the very lanes with their dead bodies, and made the whole city run down with blood, to such a degree indeed that the fire of many of the houses was quenched with these men’s blood.” (Wars of the Jews 6.404–406)
The destruction that happened then is why some people believe that these prophecies have already been fulfilled. But I think that there are some things here that don’t easily fit into that understanding, and that the disciples questions may help us out. It’s possible that all this may be future and we’re still waiting for it. But it’s also possible that Jesus may be answering two questions here: 1) when will these things happen (the temple being destroyed), and 2) what will be the sign of your coming and the end of the age. That would explain why some things fit so well with what happened in 70 AD, and why some things don’t. I don’t think that these are the types of things that we should be dogmatic about. The most important issue regarding the end times is whether or not we believe that Jesus is coming again!