1) The Temple disappeared because it's purpose in salvation history was accomplished: Christ the Lamb of God who takes away the sins of the world.
2) The Jews will be with us until the time appointed by God.
3) Any talk of the end of the world is properly focused on Christ. Christian vigilance and fidelity to Christ under trial is the main concern here: the urgency of following Him in this life. This is the theme of the Holy Father's encyclical on hope Spe Salvi--that heaven is a Person, and is personal; insofar as we are with Christ we are in heaven, and insofar as we are not with Christ we are lost and indeed doomed to confusion and auto-destruction: Hell, here and hereafter.
The End of the Temple: Christ"[T]he early Church's conviction [was] that long before its outward destruction, the era of the Temple in salvation history had come to an end--as Jesus had declared with his references to the 'deserted house' and the new Temple...Saint Paul taught that the belief that all sacrifices are fulfilled in the Cross of Jesus Christ, that in him the underlying intention of all sacrifices is accomplished, namely expiation, that Jesus in this way has taken the place of the Temple, that he himself is the new Temple..." p. 38 In Romans 3:23-25 he says "'Since all have sinned and fall short of the glory of God, they are justified by his grace as a gift, through the redemption which is in Christ Jesus, whom God put forward as an expiation by his blood, to be received by faith...'"
The word expiation comes from the Greek hilasterion with the Hebrew equivalent kapporet "designating the covering of the Ark of the Covenant. This is the place over which YHWH appears in a cloud, the place of the mysterious presence of God. This holy place is sprinkled with the blood of the bull killed as a sin-offering on the Day of Atonement--the Yom ha-Kippurim (cf. Lev 16), 'whose life is offered up to God in place of the life forfeited by sinful men'...The thinking here is that the blood of the victim, into which all human sins are absorbed, actually touches the Divinity and is thereby cleansed--and in the process, human beings, represented by the blood, are also purified through this contact with God: an astonishing idea both in its grandeur and its incompleteness, an idea that could not remain the last word in the history of religions or the last word in the faith of Israel." p.39
"When Paul applies the word hilasterion to Jesus, designating him as the seal of the Ark of the Covenant and thus as the locus of the presence of the living God, the entire Old Testament theology of worship (and with it all the theologies of worship in the history of religions) is 'preserved and surpassed' [aufgehoben] and raised to a completely new level. Jesus himself is the presence of the living God. God and man, God and the world, touch one another in him. The meaning of the ritual of the Day of Atonement is accomplished in him. In his self-offering on the Cross, Jesus, as it were, brings all the sin of the world deep within the love of God and wipes it away. Accepting the Cross, entering into fellowship with Christ, means entering the realm of transformation and expiation...The risen Lord is the new Temple, the real meeting place between God and man..." p.39
The End of the World:Christ
"...First, we must of course note the element that is genuinely new: the coming Son of Man, of whom Daniel had spoken (7:13-14), without being able to give him personal features, is now identical with the Son of Man addressing the disciples. The old apocalyptic text is given a personalist dimension: at its heart we now find the person of Jesus himself, who combines into one the lived present into the mysterious future. The real 'event' is the person in whom, despite the passage of time, the present truly remains. In this person the future is already here. When all is said and done, the future will not place us in any other situation than the one to which our encounter with Jesus has already brought us..." p.50
"This personalistic focus, this transformation of the apocalyptic visions--which still corresponds to the inner meaning of the Old Testament images--is the original element in Jesus' teaching about the end of the world: this is what it is all about." p.51