You have to take in the context. I'm not sure how many have said that the context lends reason to interpretation.
"29 “But immediately after the tribulation of those days the sun will be darkened, and the moon will not give its light, and the stars will fall from [
q]the sky, and the powers of [
r]the heavens will be shaken. 30 And then the sign of the Son of Man will appear in the sky, and then all the tribes of the earth will mourn, and they will see the Son of Man coming on the clouds of the sky with power and great glory. 31 And He will send forth His angels with a great trumpet and they will gather together His [
s]elect from the four winds, from one end of the sky to the [
t]other."
Given the whole context, this has to be speaking about the end of the world, and the physical return of Christ. Jesus was clear when He started the whole discourse by saying "Truly, I say unto you". Was He speaking truly, or was it all a riddle?