There's a bit of missing context above that verse there but it also kinda goes against the Jesus is coming soon belief:
"34Truly I tell you, this generation will not pass away until all these things have taken place. 35Heaven and earth will pass away, but my words will not pass away."
In other words there is an expiration date for this prophecy, Jesus just can't give a specific date.
Which is real convenient for Jesus since that means nobody could call him out as a false prophet until after he already died.
