If/when Nintendo goes third party, two things will happen
1-Some of the most known names will leave. Miyamoto would retire as has been rumored for some time and Iwata would be fired for failing in the hardware business and forcing them to quit that area. Other names could also quit but it is unsure, after all, they would still be independent and would still be making the software they want.
2-They would become one of the most influential publishers, being them the ones demanding things to whoever makes consoles or gaming devices by then. They could even launch their games on only one platform because the other(s) don't have the hardware/input devices/whatever they need to fulfill their vision, causing an impact on the hardware sales.
In other words, it would be sad for what it would mean, but also interesting because it would change the way the other publishers and hardware makers work.
Please excuse my bad English.
Former gaming PC: i5-4670k@stock (for now), 16Gb RAM 1600 MHz and a GTX 1070
Current gaming PC: R5-7600, 32GB RAM 6000MT/s (CL30) and a RX 9060XT 16GB
Steam / Live / NNID : jonxiquet Add me if you want, but I'm a single player gamer.