Yeah this article was pretty dumb and written with a clear bias. Nintendo hasn't had much AAA third party support since they heyday of the SNES (though Gamecube did have a decent amount). Since the Wii, third parties have chosen to just go after the hyper-realistic graphics crowd while Nintendo has chosen to go with more unique, innovative, and less expensive hardware design. It's not like suddenly Nintendo won't get AAA third party support anymore, cuz that event literally took place 25 years ago!
There is no growing third party problem with the Switch, it's the same situation Nintendo has been in for essentially the past 25 years. Switch is getting more large third party support with every passing year, as it continues to dominate the market and blow everything else away. Switch will continue to sell very well because it's got a unique hardware design that appeals to people, it's got the top notch first party Nintendo games that everyone wants to play, and it's the best way to play indies - those are the big three selling points and none of that is changing. If anything AAA 3rd party support is increasing on the Switch, not becoming a problem.