It's possible, will be easier with a bundle though. Not like it wouldn't sell separately anyway if it is having good word of mouth. Even Mario Kart was still selling around 2K-3K the week before the bundle, and was likely still selling that much throughout the rest of the year plus any rises from the holidays. Mario Kart would have made it to 1 million even without the bundles.

Never thought this was possible, but it look like it can by the end of the year

Lifetime, never, unless it gets a bundle like MK8 has. Launches aligned, 17 weeks?

Wow, I didn't think it was possible but it looks like it will actually happen.

The MK8 bundle is being discontinued in Japan.

Splatoon will have a chance at outselling it LT sometime next year, but it's hard to say when since we don't know if there will be a bundle or not. As for launches aligned, definitely this year.

From when on? (also, as a formality, source?)

Regardless, I still think Splatoon needs a bundle to pass Mario Kart 8 lifetime.

15-20 weeks seems a safe estimate.

No details on when, but it'll likely happen soon given the launch of the Super Mario Maker bundle. Here's the source.

A bundle would certainly shift the odds in Splatoon's favor.

It's currenlty 31 on Amazon.

http://www.amazon.co.jp/gp/bestsellers/videogames#2

It hasn't been discontinued just yet.