I severely doubt it. It would be awesome if it happened, but I don't think it'll make a big splash in Japan.

I'm wondering how successful the game will be worldwide?

It is said that original game sold 8 million copies worldwide, VGC has it at over 9 million (probably includes bundled copies). At this point everything that I've seen is very very much appealing to me (though I'm likely not the best representation of target group, I never played DKC game before), it reminds me of fun of NSMBW, supports simplistic way of input by holding Wii Remote sideways, and the most important feature - coop multiplayer in vein of NSMBW, but looks like less chaotic due to less people involved in gameplay and one thing that differs it from Mario game - two players controlling Donkey and Diddy have own highs and lows which will effect gameplay greatly.

More importantly though will Nintendo market the game heavily? And if they do, what kind of marketing this will be? Looking at original game, seems it won't fit for family-friendly ads, more likely it's best advertised to teenagers (besides long-time fans, of course, but I'm speaking about new audiences here). Well, it's unknown at this point whether they'll market it at all.

Though it's pretty much granted that Wii won't have this holiday season as stellar as previous was (since it really climbed high in December 2009), but could it be the hit title that will repeat (or maybe surprass) success of original game and drive Wii sales up?

 4 mill americas, 2 mill europe, 2 mill Japan... those number  could force nintendo to make Star fox and Fzero for wii for next year... Hopefully....

It's going to sell 10 million due to Nostalgia alone. Especially in Japan. They prefer 2D platformers than 3D platformers. In the Americas it might sell a lot more but it has new players to deliver now so hopefully it can do way more than expected here in the americas.

I doubt it will sell 3 million, partly because Kirby seems to be pretty big in Japan, and will be realtive tougher competition for DKCR than in the other regions.

No chance.  I think breaking a million is probably the best it can hope for.  Honestly though, I think Kirby will sell more...

I just hope it sells enough to warrant further sequels.

no even 3d mario dont make that numbers

if not a PSP monster hunter, Pokemon DS or full scale final fantasy/dragon quest dont expect anything like 1.5m

3D Mario was never as big as Donkey Kong was in its peak, though.

In Japan, VGC shows:

DKC: 3 mil
DKC2: 2.21 mil
DKC3: 1.77 mil

SM64: 1.92 mil
SMS: 0.87 mil
SMG: 1.13 mil

As long as the game is good and marketed well, I think Donkey Kong will do fine - I don't see why 1.5mil sounds impossible. Proportional to consoles sold, the Donkey Kong Country series did better in Japan than any other region (the sequels saw huge dropoffs in the west).

It depends on how it will be marketed.

I believe it will be big, between 1.5 and 2 million copies and will move hardware as well