I'm unsure how or why someone would create a thread proclaiming failure without defining what they class as a failure. It's a very nondescript proclamation of doom.
Switch is guaranteed not to be a failure already. Anyone predicting under 50m by now should be ignored.
70m+ isn't just possible, it's probable, and that is no failure.
Predictions (Made July 2019)
LTD: PS4 - 130m, Switch - 110m, XBO - 52m 2019 : PS4 - 15m, Switch - 18.8m, XBO - 4.8m 2020: Switch - 22m (Peak Year)