Mark’s Gospel is replete with theological gems worthy of the time to mine them. None is more important to the times we live in today than the entire vignette of Jesus and the disciples leaving the temple complex, Jesus’ cursing of the fig tree, and His admonition concerning “this mountain.”
The first item I would like for you to consider is that the expectation of the Messiah was also, of course, the expectation of His Kingdom’s arrival. The disciples were not wrong in thinking that way. The church age was a mystery to them.
That’s the primary reason the Jews wanted Messiah to arrive – to overthrow Rome. Then there’s the question of the Abrahamic Covenant fulfillment, especially the land aspect of that covenant.