Assuming year one games launch on time, Mario, Mario Kart, Zelda, Splatoon are all coming in 2017. The chances of any of these games getting a 2018 sequel is slim.
It will be interesting to see what first party Ninty games come in 2018. Probably a Metroid, but then what else? I see a dry spell, especially since third party gaming will probably be sparse.
To save a few bucks, I'd wait till early 2018. Could probably score a used system and used copies of all their key games after gamers sell it off in early 2018.