I found a "2013 Global Tablet Forecast" article from Dec. 11th, from the same Digitimes source you quoted, that says:
The aggressive pricing of the Nexus 7 and Nexus 10 is likely to give Google strong momentum in 2013. Digitimes Research projects that Google will become the number two tablet vendor, while Apple will retain the top spot, with its share of branded tablet shipments declining slightly to 55.6%. Factoring in white box tablets, Apple's share of all tablet shipments will drop below 40%.
The explosion in white box tablet shipments in 2012 means that Android will overtake iOS to become the largest platform in 2012. Combined shipments of all Android tablets - including branded, white box, Amazon and Barnes & Noble devices - are projected to hit 121 million units in 2013, representing 40.2% growth on 2012 figures.
That link has a metric shit ton of data, by the way. Holy shit... I thought we discussed tablets pretty thoroughly, but the info they have on there is absurd.
Let's revisit this after the new year, and go from there.
NOTE: I'm pretty sure the quoted snippet above has a type, and they mean Android will overtake iOS in 2013, instead of 2012.