I’m not exactly sure what you mean by ‘self-defeating’ in this context but you may well be right. I use ‘post-eschatological’ somewhat rhetorically or playfully to highlight the fact that, as I understand it, most of what the New Testament says about the future has in view relevant and foreseeable future events, foremost among them being the devastating Jewish revolt against Rome and the eventual ‘victory’ of the faithful church over Roman imperial paganism.

However, it seems to me that there appears on the outer rim of the New Testament’s vision of the future a final eschatological horizon consisting of the absolute renewal of creation. I am not convinced that the New Jerusalem is an image for the whole people of God. Possibly, but I am more inclined to think that it stands for the community of the saints which would suffer as Christ suffered, be vindicated as Christ was vindicated, and reign with him (the Lamb in the midst of the city) throughout the coming ages. That community of the martyrs perhaps constitutes a priesthood in the city (cf. Rev. 20:6), which is the dwelling place of God’s presence in the renewed creation. The new earth is presumably peopled by those who are not in heaven but are raised from the dead, whose names, nevertheless, are written in the book of life.

So I think Revelation 21-22 constitutes a real future hope of a final victory over death and evil, not merely a metaphor for the church, though I would argue that it is part of the function of eschatology that the people of God understands itself in the light of the new creation.

If issues such as this are to be discussed properly, this has to be done outside of the traditional categories of eschatological thought, including preterism. To my mind the reading that I have put forward (eg. in The Coming of the Son of Man) arises from a critical-realist hermeneutic that prioritizes the historical experience of the community of the text.