UPDATE: January 30th, 2020
Switch family - 52.49m (+10.82m this quarter)
-Switch - 47.30m (+7.58m)
-Switch Lite - 5.19m (+3.24m)
Mario Kart 8 Deluxe - 22.96m (+3.95m)
Super Smash Bros. Ultimate - 17.68m (+1.97m)
Super Mario Odyssey - 16.59m (1.21m)
The Legend of Zelda: Breath of the Wild - 16.34m (+1.80m)
Pokémon Shield/Sword - 16.06m (NEW)
Pokémon: Let's Go, Eevee/Pikachu! - 11.76m (+0.48m)
Splatoon 2 - 9.81m (+0.53m)
Super Mario Party - 9.12m (+1.53m)
New Super Mario Bros. U Deluxe - 5.85m (+1.26m)
Luigi's Mansion 3 - 5.37m (NEW)
The Switch family exceeds 50m one quarter after it has passed the 40m mark. Nintendo has increased their forecast for this fiscal year from 18m to 19.5m. Both Pokémon Shield/Sword and Luigi's Mansion 3 had strong debuts, pushing the threshold to enter the top 10 above 5.3m units which in turn leaves out another 5m+ seller (Super Mario Maker 2). So after its first 12 fiscal quarters, Switch has already 11 5m sellers, 6 10m sellers, 5 15m sellers and 1 20m seller. A detailed listing of Switch hardware/software shipments, including individual first party titles, can be viewed in this Google spreadsheet.
A couple of interesting links this time. Two threads were created earlier this month, asking when Switch will pass the Wii and the PS4, respectively. While the vast majority expects Switch to sell more than 100m units lifetime, it's largely ruled out that Switch can pass the PS4.