Woah, woah, woah, are we at that point already? Let's keep our heads cool a little longer before making such claims. Personally, I don't think the modern market will allow any device that isn't a phone to sell that much in any segment or even any two segments combined. Look at the insane decline in handheld sales, for instance, the market is clearly becoming partitioned and branching out. Fringe consumers have so much to choose from than before, and these were essential in the PS2's insane lifetime sales, together with an unusually long life cycle with long sustained sales, screw-up's by all competition and simply massive developer support. The Switch, as it stands, holds none of these advantages.
Time will tell, but for now, OP sounds far fetched.