I strongly disagree with this statement. The stated usage is a single person "gaming on a ps4 playing fps games and browsing or watching YouTube". The non-slim PS4 doesn't even support 5GHz! Of course nobody can predict when a product will go end-of-life but the RT-AC66U_B1 was released around the same time as the RT-AC86U. The RT-AC66U_B1/RT-AC68U is twice as popular (going by Merlin's download stats).
@L&LD for someone who is debating whether to spend £75 or £120 telling him to buy a £300 router that he doesn't need isn't helpful.
@peter s You could try using your old RT-N66U for a while using
John's fork of Merlin's firmware which is still supported. It would be superior to the RT-N16 they supply.