I don't think it will fall out of use, bel, until after it has fallen into use, which I would guess it never has done over here. As shanks rightly says, it is only people like Wodehouse (which is almost certaianly where I last read it, come to think! Gold Star to shanks.) who have used it.

As to the "eur" ending, most Brits are fairly used ot this because of "fleur", as in Fleur-de-lys, which is an common armorial device in English heraldry, therefore seen all over the place over here (even by them what knows knothing of 'eralds and the like!).

As to the 'alls of hacademe using such words, I fear that British academia has gone the way of most other cultural institutions and has dummed down - you don't hear erudite conversation in the Senior Common Rooms any more - not least because none of us have time to spend there