I haven’t modded my 3DS yet since I’m scared I’m gonna mess it up and completely ruin it forever. Besides, it’s too small for my hands now, so unfortunately I’m probably not going to be playing it much besides older Gen Pokémon games.
Fr. Wii U got taken down earlier than the 3DS, Mario Kart servers were up for about an hour after the designated time though, that was my best session of MK7 I’ve ever had too.
Most services that require internet connection on the 3DS and Wii U are gone save for Google because that’s its own private thing. You can still mod it with Pretendo or CTGP (Mario Kart specific online mod) to continue online use, but many who do not want to go through the trouble for online on their 3DS again are probably just going to switch consoles.