Nintendo intends to maintain a steady stream of releases for Switch

[PAOerfulone]

Mario, Pokemon, Zelda, Animal Crossing, and now, Splatoon, are what I classify as 'A' tier franchises. Fire Emblem, Kirby, and Yoshi by comparison are nowhere near as big, anticipated, or sell as much as those 5, so yes, I consider them 'B' Tier franchises. If Fire Emblem is over them, then I guess Kirby and Yoshi are 'C' tier franchises, but I consider them above that.
The reason why I say Smash is the 'S' Tier franchise, is because it is clearly Nintendo's most hyped and anticipated one, and it's the crossover of all of their franchises, plus some big 3rd parties. It's Nintendo's Avengers/Justice League.

And while the Switch may not need Smash in 2018, it would certainly help boost the momentum substantially than if it didn't have it.
2017 had Breath of the Wild, Splatoon 2, and 3 Mario games - One of them being Odyssey. That's going to be a VERY tough act to follow.
2018 having Animal Crossing (what I believe will be their big 2018 title) and Yoshi, Kirby, Fire Emblem, AND Smash Bros. to support it would be a solid lineup that would continue and boost the momemtum 2017 gave them, leading to a incredibly strong place for Switch sales to be once 2019 rolls in and Pokemon shows up, most likely.

And I never said anything about development time for past Smash Bros. games being long, if you paid attention to my first comment, you would have known that the main reason they took so long is because Sakurai and Nintendo waited and took a break in between each game. And as I stated earlier, I doubt that was liable to change now, especially since the Switch is doing just fine without Smash 5 at the moment. And like I said, since they approach every new Smash Bros. with a "Can you top what you just did" mentality, rest assured Smash 5 will take just a tad longer to complete than any game that came before it, to say the least.