Nintendo just tweeted information about their online service on the Switch. It announced that the service will be free until 2018; which means it is no longer set to charge this year. The free trial will launch this summer, earlier than expected.
Another announcement made by the company was about the voice chat. You will be able to invite friends, create play times, and chat with your friends on a Smart device. (Hopefully this is not the only possible way to chat.)
Nintendo also announced some Virtual Console games. Going by sources, Super Mario Bros. 3, Balloon Fight, and Dr. Mario will be released some time in the future (summer presuming) on the Switch eShop. The only disappointing factoring in is after a month, you will have to buy the game ‘again’. I used again loosely as maybe you have not yet purchased on past platforms. It is also possible there may be a free download or a discount like on Wii U eShop.
Now, it would be wise for Nintendo to say more on this matter at E3 this month.
Sources: Nintendo Website