I've always believed that he was speaking of the generation of the fig tree. (another reference in the text) The generation that would be here when the end comes. Clearly he wasn't telling the disciples that they would see it.
Mat 23:36 Verily I say unto you, All these things shall come upon this generation.
He was talking to the generation he lived in. Jerusalem was judged for all of the righteous blood shed on the earth in 70AD.
I agree. This verse gave me trouble as a new Christian, until it was explained to me. And it makes much more sense than Him telling them THEY would live to see it.