Tablet computers will outsell personal computers by 2015 globally in another sign of the shifting tech landscape, a survey showed Monday. A report by the research firm Gartner said that the shift comes despite a cooling of the tablet market in 2014 and some stability in PC sales, due to upgrades of aging devices. For 2014, PC sales will still hold a lead over tablets — with sales expected of 256 million units. The prediction came in a report which said total device sales including PCs, tablets and mobile phones hit 2.4 billion units this year.