When it comes to tablets, it appears that Samsung and Apple are likely to have a really good 2013. According to the latest parts supplier intel, Apple and Samsung are likely to ship 110 Million tablets this year. This ends up being over double the total amount of all international branded tablets combined. In fact, it's still 10 Million more than all of the white box tablets that will ship from China as well. Here's a quote with some additional detail,

Apple and Samsung tablet will dominate the market this year as the two companies are expected to ship a combined total of 110 million tablets in 2013, according to DigiTimes supply sources in Taiwan. The information comes from panel makers reporting growing orders from both international and Chinese vendors.

Brand-name international companies apart from Samsung and Apple are expected to ship 50 million tablets this year, while Chinese white box tablet shipments are said to be double that amount at 100 million for the year.

The majority of white box tablet makers are located in China and produce affordable Android tablets, selling them for a fairly low margin because of the fierce rivalry in the market.
Apparently, despite the Nexus 7 and several other options from Asus and others, Samsung is still the top selling Android tablet, and of course, Apple still reigns supreme for total tablets shipping. Despite this, it is still possible that this year will be the first year we see more total Android tablets ship than Apple tablets (when you combine all the different brands and the OEM white box units).

Source: PhoneArena