CEMU is by far the best emulator for WiiU, and the team behind it is currently working on a new version. YouTube’s member ‘reznoire‘ had access to the upcoming 1.5.0 build and shared a video, showcasing Mario Kart 8 running on it.
Nintendo has recently restored Wii U Mario Kart 8 and Splatoon online after five months of being offline.
Mario Kart 8 has been out for nine years now if you include the Wii U version. Despite the Switch port continuing to sell insane numbers since it came out in 2017, many people believed that a new installment was way past due. When the Booster Course Pass was announced instead, it was a bit controversial, with one side of people stating that it was time for a new game, and the other side believing that this was the best course of action and that there's nothing else Nintendo can do to innovate the franchise.