None of us has access to the kind of data, and the quantity of data, that would allow us to make thoughtful, meaningful predictions. Everyone's predictions are based on some combination of local anecdotes, what news one tends to read, which context-devoid numbers one tends to favor, wishful thinking (in either direction), and so on. Some people will be closer to right than others, and I'm sure they'll feel very proud that they were right. But everyone is guessing.
Part of the reason everyone is guessing is that the Switch's fate hasn't been sealed yet. It'll be interesting to see what kind of coverage it gets in the days leading up to launch and what the popular buzz is like in the first couple of months. It's entirely plausible it'll become a hot item, and also entirely plausible that it'll fail to catch on. Anyone who thinks either of those options is off the table is kidding themselves.
Also, what would possess someone to argue about this?