An amusing bit of satire can be found from Rev. Paul T. McCain’s Temple Prostitution: A Modest Proposal.
Of course, you’d think that this would actually be cutting-edge liberal theology: and it may occur in a few decades. But I doubt it: feminists loathe polygyny, so it remains forbidden in the West, despite the increasing Arab Muslim population. For similar reasons, temple prostitution is highly unlikely to occur.
Feminist intellectuals remain part of academia, and so are part of the governing priesthood of the West. Christian beliefs, on the other hand, is explicitly excluded in our secular cultures from power and influence- an exclusion happily accepted by our defeatist and retreatist clergy and laity, “waiting for the Rapture to deliver them from reality.”.
So what is going to happen? In Europe, it’s difficult to see what will happen after the end of the welfare state: some softer form of blood & soil fascism, the rise of the urban caliphates, or just a general fragmentation of the nations. In any case, there is no serious reason to believe in an unexpected rise of European birthrates, or some mass return to religiosity or family-centred morality: that isn’t how history works.
What happens is that the old population gradually diminishes, and the new immigrants rise from a despised minority to the ruling minority, to the dominant majority. So it was in the fall of Rome, and so it will be again.
Temple prostitution has no part in Islam; so it will have no part in Europe’s future.
(Other forms of prostitution are acceptable, though.)