I'm fairly convinced some form of classic games service is coming to the Switch. It seems pretty apparent to me that Nintendo chose not to prioritize it in 2017, as they likely wanted the eShop to become a healthy ecosystem for indies and third parties. Whether anyone on GAF wants to believe it or not, releasing a Virtual Console close to launch hurts third party developers. I'm a huge fan of indie games and buy tons of them and even I would purchase far less of them if VC were currently available. My guess is Nintendo wants to create a healthy environment for indies and other third parties on the eShop and once that is established, a VC-type service will launch.
VC seems to be less of a priority for Nintendo each generation.
It launched day one with Wii
It launched three months after the 3DS launch
It launched five months after the Wii U launch (though Nintendo did release a few VC titles prior to launch as a sort of "preview" for 30 cents per game)
It launched 13 months after New 3DS launched (SNES games)
Of course there's the possibility it's never coming (beyond the NES games you receive for subbing to the online service), but I'm not even remotely convinced enough time has passed since the launch of the Switch to believe this is a certainty. Heck, Nintendo could launch the service out of the blue sometime in 2019 or 2020 for all we know. They do completely random things like this often. No one expected New 3DS to get its own subset of a VC and after many, many years of nothing Pokemon-related on the 3DS VC (and after an extremely long period of zero VC releases on that system, period), Nintendo and Game Freak surprised everyone.