Why do people think that Nintendo could go or should go third-party?

[KungKras]

Aeolus451 said:

In short, nintendo is not that good at making home consoles and the handheld market is skrinking. What's keeping people from playing (and buying) nintendo's games is that people have to buy it's home console which they often don't. If nintendo makes their games available to consoles, pc and mobile, their would sell very well and it's brand would expand without them having to invest in hardware for the games.

Nintendo is great at making consoles. Their hardware is usually very well engineered.