The best way to gauge how any game will sell is to compare it to other games on that system. For instance: we know that many games on the 360 have heavily frontloaded sales in NA, while many Wii games in NA have smaller debuts and make their sales over a period of time.

DQS has sold roughly twice what the nearest third party game(which is an origianl title) in Japan has sold. I'm aware that DQS was originally a tv plug-and-play game, but that has little bearing on how the game has sold on the Wii(in my opinion). Without checking to make sure, I believe that DQS and RE: UC are the only third party games to even crack 200k in Japan. Japan has shown they don't mind buying remakes(check the DQ and FF games on other systems) by the boatload.

I'm not saying the right third party games won't sell in Japan. I know that a proper DQ or FF game would move a ton of systems over there, but that's kind of the point. Many of the people that own or are buying Wii's in Japan are only interested in Nintendo's traditional and new casual games. Traditional gamers on the Wii buy the Zelda/RE/Fire Emblem-type games in the first week or so, and then sales slow to a crawl.

I hope that Tales ends up being the traditional third party breakout hit that the Wii needs in Japan. The Tales game are fairly popular in Japan, but not that popular. Like I said, I'd be pleasantly surprised if Tales reaches 500k lifetime sales in Japan. It's quite possible, but not likely given Wii third party sales, and traditional game sales in general(in Japan).

500k in Japan alone is impossible. My prediction would go:

200k+ Japan

400k US

350k Others

More or less, those numbers are very hopeful, and the games sales will be largely review based, imo.

As for Nintendo in Japan, they don't exactly "need" anything. If Nintendo is in dire "need" of anything in Japan, then Sony and Microsoft might as well just stop shipping units to the country, because they're dead.

 Nintendo does need third party games to sell in Japan. Financially, at this point, no they don't. But as the Wii ages, and a new generation approaches, they definitely need third party sales to pick up there. Most of the Wii's exclusive third party support is coming from Japan, and quite a few Japanese devs have already stated their disappointment at sales in thier territory. Nintendo doesn't need the Wii to become another N64 or GC in Japan, they need to be a safe haven for third parties like the NES, SNES, PS, and PS2.

The X Box is nothing more than an outreach program to Japanese devs at this point.

The PS3 is getting whooped, but it's far from being over. I think Metal Gear will help, but Final Fantasy is going to move some systems. How many? Who knows. Things aren't looking good for the PS3 there, but it's not hopeless. If nothing beyond Nintendo games sell on the Wii, all of those third parties are going to go somewhere with their more ambitious projects.

I'd expect ToS2 to sell over a million without as much difficulty as the previous episode. The install base is there, the name recognition is there, so I'd expect people to buy it without as much hesitation as before.

It's really hard to say.

I hope 800k in Japan alone. Anything under 400k is lame.

I know... I'm just hoping RPG's take off like a rocket on the Wii.  

Maybe if Namce didn't release Tales games so frequently they would sale better. Anyways, I'll give it 750k WW this time next year.

I hope it ends up platinum, but that'll only be if they market it well. A cover of NP isn't a bad start so far.