If you look at the whole chapter (Mark 13), verses 1 & 2 give the reason for the disciples questions in verses 3 & 4. Verses 1 & 2 are discussing the Jewish temple and a prediction by Jesus that it will be leveled. So, naturally, the disciples questions in verses 3 & 4 are directly related to that.
At the other end, verses 28-31 are a sort of summary parable describing the events just described (verses 5-27) and Jesus describes these things as being fulfilled within "this generation." An unbiased reading would place everything between verse 5 and verse 27 as something Jesus was predicting for (then) contemporary Jews. Even if one doesn't understand how verses 24-27 could have happened back then, the surrounding context argues that Jesus was expecting those things to happen within that 'generational' time frame.
Claiming that verses 5-27 must have a dual fulfillment is, in reality, an admission that they don't understand all of what Jesus was talking about.
It is only starting at verse 32 that there is a hint of some future judgment that the disciples have to be ready for. The events in verses 5-27 have the disciples being given a way of escape and salvation from what was predicted for the temple and that Jewish generation. (verses 14-20)