Android's share of the market is forecast to reach a peak of 48.8% in 2013 compared to 41.5% in IDC's previous forecast. Android's gains come at the expense of Apple's iOS, which is expected to slip from 51% of the market in 2012 to 46% in 2013.
Windows tablets are expected to only account for a tiny fraction of the global tablet market in 2013 (MS only has so many employees to give them to), but Windows RT and Windows 8 are expected to make up 10% of the tablet market in 2017.
IDC has also made some unsubstantiated predictions about the ereader market. They believe shipments peaked in 2011 at 26.4 million before dropping to 18.2 million units in 2012. IDC expects shipments to increase slightly in 2013 and 2014 before beginning a gradual and permanent decline in 2015.
I won't comment on the tablet predictions other than to note that IDC's accuracy rate is so poor that they had to correct themselves, but I do believe the predicted number of ereaders shipped is woefully inaccurate. It does not match up with the info I have on ereader adoption.
Pew reported in January that ereader ownership in the US grew over the holidays to 26% from 19%. Market surveys from other countries indicate that ereader shipments also increased in 2012 and are expected to grow in 2013, so it's not clear where the drop in ereader shipments came from.