I'm thinking in Matthew 24, Jesus is speaking to His Jewish Disciples concerning the generation that sees all 'these things' is not a reference to years or time, but a direct reference to His chosen ones the Jews. It is the Jews who will not pass away seeing all these things ~
The devil wants to wipe out the Jews, and from Scripture we know God will not let that happen ~ The Lion of Judah, the Root of David, the King of kings will return to Israel, and touch down on earth among the Jews seeing 'all these things' ~~ in Jerusalem still standing to start His Messianic Reign~