But, it has been an amazing system seller. How many units would have been sold in that same period without Let's Go, but with NSMUDX in its place? Look at PS4 sales there at the same time?
For the PlayStation 4, we can compare with the launch of Monster Hunter World in January.
Week 1 : hardware sales were up by 218% YOY (+100% for Switch).
Week 2 : hardware sales were up by 204% YOY (-15% for Switch).
Week 3 : hardware sales were up by 126% YOY (-28% for Switch).
Of course, sales would have been even worse without Let's Go, but this isn't the subject. Nintendo wants to ship 5M more Switch this fiscal year than last fiscal year. They will do better than last FY, because they did better than I expected during Q1&Q2 and because Smash is huge, but they won't ship 20M units because Nintendo Labo bombed, Pokémon Let's Go wasn't as big as some people here thought and Smash launched to late.
And, maybe it's not best to use the market which is in decline as a test for the rest of the world.
I use Japan because it's the only market where we have numbers available now. For UK, we just have numbers for the Black Friday week. For US, we just have some tweets without anything concrete (NPD report will be really interesting, but it isn't available now) and for other contries, I think we have nothing.
And Japan was a reliable indicator for last FY, Q1 and Q2. Obviously, the reception of a game can be different between Japan and the West, but I doubt hardware sales will be really different for Q3 in different markets. If hardware sales are only slighty better in Japan, I think they will be only slighty better in US/EU.