There are two matters here.
Blessings and Curses
The first is the prophecies made by Moses in the Torah. They occur in several places but the main two are found in Deut 28 and Lev 26. In both places God promises to prosper Israel for obedience and bring punishments and disaster in the form of the great four judgements of "Sword, famine, wild beasts and plague" (Eze 14:21, see also Jer 21:9, 24:10 etc.)
Fulfilment
The judgement metered out on the Jews that culminated in 70 AD destruction was not the first time it occurred. Such judgements had been occurring for 1500 years before such as:
- the numerous invasions recorded all the way through the book of Judges - each time the people were wicked they were oppressed and had to be recued by another judge.
- There were similar events in the life of Samuel as recorded in 1 Samuel
- There were similar punishments and judgements during the time of Rehoboam, Asa, and many more of the kings of both Judah and Israel.
- Eventually, the northern kingdom of Israel was taken captive in about 722 and ceased to exist because of its continued wickedness
- The unremitting wickedness of Judah also resulted in its complete capture after the third campaign of Nebuchadnezzar in about 586 BC
- The problem was not solved even in Malachi's time as the people struggled to live because of their unfaithfulness.
Finally, after the Jesus the Messiah arrived and the Jew rejected even THIS call to faithfulness, the prophecies of Daniel 9 came to fruition.
Therefore, I do not believe that all the judgements came on the last generation - it was just that after more than a 1000 years of unfaithfulness in representing the name of the LORD, God decided that continued punishments were obviously not effective and the Christian church was commissioned.