Matthew 21:12-22 narrates Jesus cleansing the Jerusalem temple that had become a "den of robbers." Immediately following that event is Jesus' curse upon the fig tree, pronouncing that it would no longer bear fruit.
Jeremiah 7 & 8 is an oracle about Judah's exile into Babylon & the soon-coming destruction of Judah's precious city & temple.
The "den of robbers" and the withering of the fig tree are both clearly alluded to in Jeremiah 7 & 8 (particularly 7:8-14 & 8:4-13).
Isn't it reasonable, therefore, to associate the message of Jesus in Matthew 21:12-22 with the message of Yahweh in Jeremiah 7 & 8?
If Yahweh cleansed his temple in the days of Jeremiah, that same message of cleansing was being repeated in the days of Jesus. Since the covenant-breaking of Judah's leaders was being repeated, the message of Yahweh's covenant-faithfulness was being repeated. The major difference between these two visitations was that Yahweh would send his own Son to die in the place of Judah, to be faithful to Yahweh's covenant, even unto death, so that the old Israel would finally die and a new Israel raised up to newness of life in union with Him.
Salvation would come upon Israel through judgment in 70 A.D, but the old Israel and it's "den of robbers" in union with the first Adam would die in the judgment upon Jerusalem. Those who would not give up everything to follow Jesus, the second Adam, would wither and die like the fruitless fig tree of the old Israel. Only those who took up their cross and followed Jesus would be constituted as members of a new Israel, a new and living body--the body of the faithful Son of Yahweh (Ex. 4:22; Hos. 11:1; Matt. 2:15).
Jesus came to his own and his own received him not. He came as the faithful firstborn "Son" that Judah repeatedly failed to be after receiving his inheritance. The scepter departed from Judah once Jesus came, to whom it belonged (Gen. 49:10 MT); and unto him is the gathering of all nations in him as promised.