its hilarious to me that the OP seems to fundamentally not understand Nintendo's audience whatsoever. PC gamers generally are fairly hardcore or people who just play there in their limited free time since they are working on the computer anyway
what sells for Nintendo (audience wise) are the families and casual audiences, who want to play in the open in a room together. also they sell (handhelds) well to the on-the-go likes to game whenever younger crowd. neither would be logically targted with the PC move you are suggesting
I am not sure if mobile is a smart move, I think if they integrated a mix of a phone and handheld that might be a good move however if they are specfiically going to allow their games onto mobiles in general then they should severely limit it. they still are insanely successful with handhelds and obviously I think they are smart to maintain their hardware business in general
as soon as you abandon hardware not only do you lose a lot of control over WHAT you do as a video game company, but the quality in general seems to dip too (cough Sega)