Using all of 2008's currently available data, the Wii has sold 53.7% of all next-gen consoles, worldwide.
So because of that ratio (53.7%), we can assume that the Wii should eventually get to that point.
Mind you, the total of 2007's numbers had the Wii at 51.1% of total console sales - so it's margin has actually increased this year over last year's, as of today. However, one should note that the Wii was at 52.0% on the same week last year, so it dropped by 0.9% in December. If the same trend occurred, the Wii may make it to 52.8% on the year.
Of course, it could go the other way - only one of the 2 HD systems got a price cut this year (X360) versus both getting price cuts before Christmas last year (X360 in August, PS3 in October/November).
Back from the dead, I'm afraid.
