How Will Nintendo's 3DS and WIIU Online Play Shut Down Affect Players?

Nintendo recently announced that they would be pulling online play from the WIIU and 3DS. How will this affect games and software that rely on it?

Nintendo is ending Wii U and 3DS eShop service

Nintendo Is Closing The 3DS & Wii U eShops And Has No Plans To

The Nintendo 3DS And Wii U eShop Are Now Closed

Nintendo Is Officially Shutting Down The Nintendo eSHOP

On Its Deathbed, Can We Admit the 3DS Was a Disappointment?

Play these 3DS and Wii U games before their online features are

Nintendo is shutting down the 3DS and Wii U eShops in late March 2023

Nintendo Has Removed Mario Kart 8 And Splatoon From Wii U Network

Wii U - Wikipedia