Considering the Wii U had the miiverse, i really don't think text chatting for online is out of the question at all (i know they're different beasts, but the point is Nintendo did have a way for us to communicate with each other in a sense, so to assume text chatting will be there seems resonable to me). I mean Nintendo can't just allow their online service to be as lackluster as it has been, charge for it, and assume everyone will be cool with that. I know we'll be getting classic games with new online functions as well, but even still, that alone isn't enough.
Point is, i can definitely see this happening. I'm very curious to see whay the Switch online program looks like next year.