Does this seem too high, too low or just right. I reckon 9-10 million possible but I'm not sure about 13 million.

Here's the link:

 http://kotaku.com/375889/analyst-gta-iv-will-smoke-the-competition-with-13-million-copies-sold-in-2008

If that was the case I wonder what the share percentage would be? PS3 50% to 360 50%? Say 6.5 million sold on each exactly.

It might be possible.

CoD4 has sold 8.22 Million copies to a combined 29.4 million PS360 owners. (28% attach rate)

Assume that there might be close to 44 million PS360 owners at the end of the year (~20 PS3 & ~24 360). A 28% attach rate for GTA4 would give you 12.32 million copies.

8M for CoD4 ... just WOW !

even if CoD4 was released at Xmas, I suppose GTA4 should be able to do 10M-12M at the end of 2008.

Well it is possible :).

After reading that they expect sales of 13million for the first year i went look for some past data on GTA:SA sales and this is what i found. Talk about crazy legs, 1.5mil sold between sept 07 to march 08.

As of September 26, 2007, Grand Theft Auto: San Andreas has sold 20 million units
As of March 26, 2008, Grand Theft Auto: San Andreas has sold 21.5 million units according to Take-Two Interactive.

One million units sold in the UK in nine days makes video game history for British developer Rockstar North

UK gaming sales statistics agency Chart-Track has confirmed that in its first weekend on release GTA: San Andreas broke all previous records to shift an obscene 677,000 (estimated) copies in Britain alone. The European total is reckoned to be in the region of 1.5 million, with a similar quantity expected from the North American debut too.

60% 360

40% PS3 

Not entirely unconcieveable to be honest, GTA IV is a huge franchise and this is without a doubt the most anticipated multiplatform title of this gen so far!

I still find this hard to believe, even taking into account that this is a prediction of retailer shipments. 13 million before the end of the year? Lifetime, OK, but in 2008? I don't think so...

Keep in mind that this is predicting Grand Theft Auto to DOUBLE the sales of Halo from last year.

Also, no game outside Wii Sports/Wii Play has even hit 8m yet in this generation. Expecting another 5m on top of that seems doubtful.

Or yet another way to put it: take the top-selling game lifetime on the 360 (Halo at 7.5m) and the top-selling game lifetime on the PS3 (Motorstorm at 3m), add them together and you're still a solid 2.5m short of that prediction. So I don't think I'm going out on a limb by saying this is a long shot to happen.

 So a ratio 1.5 to 1. In favour of the 360. I wonder what percentage of GTA 4 combined (PS360) will be sold in the Americas region? I guess say around 70% in Americas of the total sales of GTA 4.