Switch is essentially an example of games (quality and quantity) above all else contributing to sales. As long as you simply have a healthy lineup of diverse games that appeal to a relatively large audience, you'll do ok. I suppose the convenience of the Switch's portability helps as well, but it's not the key element. The whole casual thing and motion controls for Wii I've always said was a completely overblown reason as to why Wii was even successful in the first place, and Switch is proof of this.
"We hold these truths to be self-evident - all men and women created by the, go-you know.. you know the thing!" - Joe Biden