The whole point of the "can third party games sell" question is "can games sell without being promoted by the first party." The issue is not who made the game, its who is paying to advertise it.

So in this particular discussion, "second party" games should be grouped with "first party" ones. You can bet Sony will promote the hell out of their big "second party" games this year.

If I was a betting man, I'd say Need For Speed. On a WW basis, it outsells Madden by a wide margin, and AFAIK there's no established million-selling franchise among the exclusives coming.

 Go wii fanboy go, for some reason wii fanboys are always the most  ignorant ones.

Those games were launch titles. The Wii absolutely DID NOT have such a large advantage in user base at that time.

The last few multi-platform titles are more telling. Spider Man 3 on the PS3 initially outsold the Wii version; now the Wii version is selling better, and it's rapidly approaching the PS3 version (they're withing 10k now, or 7% of their total sales, and at this rate the Wii version will outsell it in total within a month or so). The most recent multi plat titles have been Harry Potter, The Bigs, and Transformers. Transformers has sold marginally better on the Wii (and is pulling away slowly), the Bigs has sold twice as well on the Wii, Harry Potter more than three times as well.  

The Big sold more on Wii cause its Wii's only baseball game the PS3 has 3 the bigs, MLB2k7, and MLB the Show 07 (the best baseball game on any platform)

Harry potter + $500 - $600 console = fail

potter isn't exactly the type of game that you would think of when you think PS3 owner.

transformers and spiderman are the only legitamte ones.

 I say that madden will hit 1 million first fallowed by Call of duty 4 because of the head start madden has.

 Sure thing, buddy.

GTA IV or MGS 4, whichever comes first (though, MGS 4 would need a head start of at least a month to beat GTA IV). Apart from the Final Fantasy XIIIs, nothing else strikes me as a million+ seller.

 I sincerely hope you were just trying to be funny.

A $60.00 PS3 game sells 100,000 units would generate $6 million in revenue.

A $50.00 Wii game sells 100,000 units would generate $5 million in revenue.

That's hardly making up he difference if it costs double or triple to produce a PS3 game vs a Wii game.  

 Then again, a mutiplatform game isn't bound by this console specific problem as development costs are amortized across all platfroms.   

 I'm willing to bet that Madden PS3 will outsell Madden Wii.

 First off a 60 dollar game is not 6 million in revenue, much like a 50 dollar game is not 5 million in revenue, and as you said it's a multiplatform game, which means 360 and PS3 shares development cost and Wii - PS2 shares development costs, overall the 10 dollar difference IS to make up for the added development cost on the 360 - PS3, this has been said plenty of times by MS and Sony themselves.

As far as the original question, I forgot to answer, I'll say FFXIII, MGS4 and GTA4 are the only ones that I see  being sure 3rd party million sellers on the system, sure UT3, CoD4, Madden, etc can be too, but it'd be way more difficult, I'm gonna say MGS4 or GTA4, whichever comes out first.

 I've already taken that bet with someone else, but I will match it with you: I bet the Wii version will outsell the PS3 version. And luckily, I have recent evidence to support my hypothesis!