I've been following this for awhile. Nintendo has long been on pace to have 20 ten-million-selling games between their two current consoles, but now the goal is within site, with enough games announced to potentially reach 20 total.

Already there are 12 games which have sold ten million.

Wii Sports - 45.07m
Wii Play - 23.31m
Nintendogs - 22.39m
Wii Fit - 19.53m
New Super Mario Bros. - 18.67m
Brain Age - 17.42m
Pokemon Diamond/Pearl - 16.82m
Mario Kart Wii - 15.89m
Mario Kart DS - 14.99m
Brain Age 2 - 13.76m
Mario and Sonic Olympics - 11.12m (6.93m Wii, 4.19m DS)
Animal Crossing: Wild World 10.81m

There are 4 more already-released games with a solid chance.

Super Smash Bros Brawl - 8.43m
Super Mario Galaxy - 7.95m
Super Mario 64 DS - 7.51m
Mario Party 8 - 6.54m

And there are 4 more announced games with a solid chance.

Wii Sports Resort
Pokemon HeartGold/SoulSilver
Mario and Sonic Winter Olympics
Wii Fit Plus

I'm not predicting all these games will make it, but this is the first time the list of potential ten-million sellers has reached 20 concrete, non-laughable entries. What a milestone this would be.

And this is despite the failure of Wii Music and Animal Crossing: City Folk, which I thought would be needed.

Super mario 64, Mario Party and Mario and Sonic have no chance of making 10 million, for the rest I think they will pass 10 million each game

We can add new zelda or mario, wii-(write here any name) or new nintendogs-brain training and ninty could make the 20 ten-million sellers

What's your rationale for Mario and Sonic Winter Olympics passing 10 million when the first game didn't (on one platform, of course)?

Pokemon Platinum could make it

Erm... Clearly I counted Olypmics combined sales. Without that it becomes a longer shot.

Mario 64 I think will make it. It shipped 1.38m in each of the last two fiscal years, which were it's forth and fifth years on the market, to reach 7.50m shipped. So I don't know why it would start dropping in it's sixth or seventh year with DS still going strong.

Mario Party 8... Admittedly a long shot. Some others like Mario Party DS and Link's Crossbow Training are also long shots... But they are all on the table because of high second-year sales. I suppose Pokemon Platinum is also a long shot, but I'm not sure how it will fare once the more-anticipated HG/SS are out.

Wii Fit Plus? When was it announced?

Not announced, they took out a patent application in that name. It's on the news section.

But a patent application often never eventuates. Especially with hardware come to think of it. Apple has enough gaming console patents to start, well, a gaming console I suppose

I already knew that, I thought there is some new info. 

A patent actually means that they started considering it as a future game only now. 

They trademarked the name, with a logo, just ahead of E3, and after the name already showed up in a retailler listing earlier this year. It would be really surprising if it wasn't confirmed at E3.

Well I think we need some other announcements to reach the goal of 20 million sellers. Out of the four games you mentioned which are crawling to one million currently, I think Super Mario 64 is the one with biggest chance because it had very steady sales over the last years. Mario Galaxy and SSBB could very well end up somewhere between 9 and 10 million units sold, and Mario Party 8 making it to 10 million is completely out of sight, especially with the successor being overdue.