The end of Wifi back in the NDS/Wii era was mostly because of the shutdown of the GameSpy servers, which were used by Nintendo. Sure, I don't think they cared much about keeping Wifi alive, if that would have even been possible (I don't know if there are any important GameSpy related URLs or certificates inside the games), but it might have lasted longer. I still don't think the end of online activity on the 3DS is near yet, but well anything is possible.