Nintendo killed the 3rd party support with their politics. The result was that all games that want 3rd party games, the large majority, bought PS or XB consoles. The only market that Nintendo has is basically kids and families, even the "hardcore" gamers aren't there anymore in a decent number as Bayonetta 2 sales do show (Just Dance on Wii U did better than it).
Ninty's issue is that they are stuck in their 90's mentality and don't seem interested in changing it, so people got over it and migrated to other systems. They tried to change to a casual gaming company, but didn't counted on the mobile phones stealing their market and ended up just doing a quick cash in but alienating their market even more. Now they are out of the performance arms race, out of the 3rd party release loop and out of the touch with what people want.
In the end, getting a Nintendo console today means getting less games than the others and way less variety, with a bunch of titles oriented to a more young demography.
