In my eyes the main contenders for this are few and go as follows...

-Final Fantasy XIII

-Demon's Soul

-White Knight Chronicles

Over the years we have seen quite a few JRPGs yet none of them have been really what the crowd wanted. Lost Odyssey comes close yet with numerous technical issues it failed to meet expectations. it seemingly has stabalized itself somewhere at 0.8-0.9mill last time I checked.  Valkyria Chronicles, claimed to be the best JRPG(of sorts) so far this gen, is still simply far to niche of a title to bring in huge sales, it has capped somewhere just above 0.50mill.

Now we have 3 JRPGs coming within the nxt years time frame. First will be Demon's Soul, next will be WKC, then FFXIII.

Argument for Demon's Soul:This game will release first. In a month's time we will have this game on our store shelves. It was already released in asian territories and didnt truly leave a huge mark, with only .13million sales so far. Yet this could possibly be due to the fact the game looks nothing like a JRPG, actually this game is much closer to games such as Oblivion(a WRPG). This could possibly make this game appeal to the American/European audience much more. This game has a few months on it's competition, giving it the most time alotted for this feat.

Argument for White Knight Chronicles: This game is technically the most popular Japanese RPG to release on the HD console's in Japan, to date. It has bolstered arond .39million sales so far(although I heared articles that put it closer to .5mill already) in japan alone. This definitely gives it an edge over Demon's Soul. When it finally makes it's western debut early 2010 it could very well make it to 1mill.  Yet can it do this before FFXIII drops, which is rumoured to be hitting in around March or April. The game is made by the famed Level 5, responsible for the Dark Cloud series, which to my mind 1of 6 JRPG series i can even think of that broke 1mill on a high end console(these are FF, DQ, Dark Cloud, Star Ocean,Legend of Dragoon, Tales of...). This could possibly garner in some good publicity for this game, especially now after hearing they are adding Georama, a facet of Dark Cloud into the game.

Argument for Final Fantasy XIII: This game doesnt trully need an argument. With this title it is not really a question of WILL it hit a million but WHEN? The game will sell tons, yet for this arguement it is the last to release which gives the other to the opportunity to claim this title first.

EDIT!!!!

I realize the error in my question. I forgot all about FFXIII releasing in Japan first this christmas.

Lets just say for argumentative sake we will not count sales of FFXIII till it has fully released world wide(when NA and EU versions are released next year.).

Honorable Mentions-

Star Ocean: The Last Hope has a very small chance of hitting 1mill. its at .5mill now, and there will be a PS3 version finally being released soon yet I highly doubt its enough to get it to 1mill. Also not sure of this game's release date.

Magna Carta II: I simply do not see this happening. The game is pretty, yes. Yet I have the strong feeling just like its prequel it will underperform.

Resonance of Fate: looks cool but It doesnt have a strong following yet and is trying to find it's base.

Why is any game except FFXIII on this list? :P

Final Fantasy 13 will do it in its first week on sale.

Resonance of Fate will definitly hit 1 mill+ and also SO4 total sales will(PS3,360) will too or it might just hit a mill on just PS3 i mean it was able to get 500k+ on 360

FFXIII first day!

like i said its not a question of WILL FFXIII make a million, we all know it will on Day one no doubt. Its more so a question of can the other games pull it off before FFXIII ever even sees the light of day?

FXIII. Within 24 hours of release.

That's not even a question. None of those other games will be anywhere near 1 million by the time FFXIII releases.

Yea, but which game will hit 1million FIRST? Remember, FFXIII is the last of these to come out.

No doubt FF XIII will be the first one to hit 1 million.Most likely SO 4 will hit 1 million too when it's released on ps3.