How sustainable is a move from FP2 to FP3?

I’m using my FP2 for nearly (and just) two years and it’s working “fine”. The fine is in brackets because of the endless WiFi-problems (I’m using LoS 17.1 and an AVM FRITZ!Box 7490) and unfixable disconnects.

So to be honest there is likely no valid reason to buy a FP3 ;). But I want to discuss, so do you consider recycling FP2 and getting a new FP3 to be in any way sustainable? Can this ever be sustainable? What happens with a sent back Fairphone 2?

Thanks for sharing your thoughts!