we don't have official confirmation on how nintendo's new online play system would be managed. their servers may be about the same as always. the only thing we know is that mobile phones are now a part of the equation.
The goal of the Switch seems to be to deliver the home console experience anywhere you go, but one thing that seems like it will always be missing is online play. there are too many places where you just don't have access to wifi, and not everyone can run a mobile hot spot indefinitely. we've got data caps to worry about.
I like to think that Nintendo are good designers, that things fit together in a way that improves the end product, so I feel like there should be a real reason for the mobile phone integration. If mobile phones are going to be required, it's likely because they add some functionality that the switch needs, but inherently can't have. in this case: a constant online connection.
This brings me to my main point: what if we're paying two dollars per month to have our Switches connect to the internet through our phones without using up our data caps? Nintendo released a price range for the online play, not a fixed price, and it would make sense if the price you pay is based on which mobile carrier you use.