Which is kinda doable, considering

If Nintendo can keep Nintendo Switch stock up in Japan, Switch has a seriously good chance of catching back up to the 3DS after it's price drop, pretty quickly.

Was 4k the lowest 3Ds have been?

Who would have expected that just a couple of weeks ago?

Though I'm not sure if Nintendo will keep this up for long now that Obon week is over

Consdering MHXX is coming out with a bundle for switch soon It might just be able to keep up or even get back ahead really quickly. I don't expect good numbers for the MHXX, but it is a limited edition switch and if enough of them were produced hardcore MH fans would buy it just for the limited edition switch.

Didn't know there's a bundle coming with MHXX. But anyways, this will become a nice battle between the two consoles

Btw, how does the Switch compare to the Wii or the DS right now?

I wouldn't know, I don't have numbers for them, but I recently saw a chart somewhere with the 3DS post price cut heading close to the DS so its definitely tracking behind the DS right now.

Switch has sold 396k so far this quarter, with 7 weeks left to go.
Last quarter, total sales: 475k
Last quarter, first six weeks: 285k

Since the Switch shipped 520k for Q1 FY3/2018, we can probably expect shipments of at least 700k this quarter, assuming they ship an average of at least 45k for the remaining seven weeks.

Judging from the July NPD, the Switch saw a more modest increase in shipments in the rest of the world. In the US, it went from an average of 43k per week to 55k per week. (This is a conservative estimate, since post-Splatoon weekly sales would average 68k) If we compare that against shipments, we can probably expect at least 800k in shipments to the Americas, and 750k everywhere else.

So the Switch can at least reach 2.25 million in shipments this quarter, with the potential to do much higher numbers if the Japanese weekly sales actually indicate significantly increased production. (70k average in Japan, 68k average in US)

Best case scenario:
Japan: 890k
Americas: 950k
Other: 880k
WW: 2.72M

Nintendo couldn't keep up with demand from launch, what really helped is bigger shipments of Switch.

It seems that Nintendo significantly increased Switch shipments on other markets recently, we had recently info that "All GameStop stores restocking Switch tomorrow for the first time since launch". In other words, it seems they priorities Japan market because Splatoon 2 launch and now increasing shipment on other markets.