Well... i dunno. Nintendo expanded with the Wii but then contracted with the Wii U. I'm not even sure one can say the Switch is expanding anything rather more than trying to unify the portable and console spaces.
Now, i can see where he is coming from. Sure we can say that Nintendo appeal more to casuals and the other two to hardcore. So... here is the problem. Nintendo wants to make a profit on hardware sales, and that audience gives them that and a few first party sales. As Harrison admits, his kids still play Zelda and mario kart, both of wich, i will add are out for the Wii U aswell.
MS and Sony go for the hardcore cause those buy alot of games. They want to sell games. The hardware is sometimes secondary and they are willing to take a loss.
Now what is more valuable in expanding the market? A few costumers that buy the hardware and a couple of games or one gamer that buys the hardware and dozens of games? I am inclined to think that it's the second, and i think that is the angle that MS and Sony are taking and it's not necessarely worse than Nintendo's.