I think that the only reason to invest in an expensive new fixed business seat would be if it gave a strong additional advantage to AF in getting long haul J passengers (which as mentioned I doubt it would do in the first place). If you do it for MH C passengers it is, simply, a complete waste of money because there are so few of them that the investment is simply not worth it. What is more, if you do this, you will make your long haul J product even LESS competitive than currently is because even if the service was exactly the same as the one offered today, the psychological impression of your long haul J pax would be that they are treated like 'second class citizens' (quite literally ) by AF while they are treated like first class ones by BA, LH, and the ones (because you 'downgrade' them to premium eco/intermediate class on the medium haul). So to me, the pragmatic approach would be:

keep the old (reclining) seats with the current configuration (3+3 with medium seat blocked) and keep the little cash available to create the best possible long haul J and - if you believe in it which I don't - long haul P products.