If there's any truth to this, it looks phenomenal! And it would be the first Universal expansion I've been excited about since WWOHP. I do doubt this will be on that level–HP is more of a household name, and the addition worked so well partially b/c so many kids (myself included) dreamed of becoming a part of that story. I love Nintendo and grew up playing Mario, Zelda and Pokemon, but don't think it has the same claim to fame. I'm mostly hoping that the theming will compete with Hogwarts/Hogsmeade/Diagon Alley. The Mario Kart-based attraction looks great, but how "immersive" the lands are (whether most are simple playlands, or really make guests feel they're stepping into a video game) will probably make or break the experience for me.
Unrelated: Anyone else surprised by how few Pokemon attractions there were on this map? It's easily the most merchandisable Nintendo franchise, but it seems like there's only one small area for it (possibly a playground or children's show).