If Nintendo ever ports one of their older titles to mobile they'd reach it pretty damn fast :p

They seem dead set on not doing that, though

On Nintendo's next system.

Majora's mask 3D and Zelda U, combined with continued sells from other games should reach 10. (92m in total)

If Ninentendo play their cards right with the next home console and Zelda, I can imagine the next game doing 8m (an Ocarina styled game on modern tech). Something we haven't seen since 1997. If Twilight Princess came out in 2003 instead of 2006, it would have came close to ocarina of times sales.

Regardless of what they do, it'll happen in the next 5 years.

Majora's Mask 3d and Zelda U will do a lot more than 6m combined (Zelda U alone might do 6m+).

When conting spin offs, it's gonna take another handheld and home console zelda after MM 3d and zelda U) to cross the 100m mark. So, 2017/2018.

p.s: With digital sales (including VC), it could do it sooner than we think.

Anyone else sad that Crossbow training outsold most of the other Zelda games?

In a way, but it was bundled with the zapper so that definitely had something to do with it. 

I'm sad that Phantom Hourglass has outsold many of the greats! 
No, let me rephrase that: I'm sad that the Zelda series hasn't sold more.

Mario Kart Wii alone sold like 35 million.

Wii Sports sold like 70 million I think?

And Pokemon? Seeing how the main series is on Nintendo handhelds and the handhelds always sold better it's not that surprising.

Twilight Princess outsold OOT and will probably hit 10 million in the future, Zelda Wii U will good and MM3D will defentily pass OOT3D from the looks of it.

I'm gonna guess by the end of the 9th gen. They'll continue remaking old games, which will sell, and next gen will probably have a few new entries. If we assume each of them sell 4 million, that would be 12m in new games and I think remakes + spinoffs could make up the remaining 6m. Of course, this also depends on how much their 9th gen system(s) sell.

Edit: And this is assuming Zelda U and MM3D sell 0 units, as I forgot to include them in my mathematics. So if we assume that between Zelda U and MM3D they sell a total of 8m lifetime (5m for Zelda U and 3m for MM3D, both safe predictions, imo) then they would only need to sell 10m units in the 9th gen, which is extremely doable. 

I think it will be in 9th gen

Wait what? Oh I thought Ocarina was t 8m.  And yeah, when combining both Wii+GC, it still outsells OOT. Completely forgot about the gamecube release.

Next gen, when another handheld and home console iteration come about. That is, if they right the wrongs they've committed this gen.