A couple weeks ago, the D5503 aka Sony Amami or Z1S was discovered in the FCC database, as well as the Sony D6503 and Sony D53XX (D5322, D5303), hinting at a couple of new products in 2014. Well a few weeks later, and even more model numbers have been discovered!
Four model numbers in total were leaked, with the first three (D2005, D2015, SGP521) being discovered through an Indonesian Postel Regulatory website, and the last one (D2303) being discovered through the AnTuTu benchmark.
Speculations are that the SGP521 will be the 2014 LTE version of the Xperia Tablet Z, which has a similar model number of SGP321. There are now a total of 7 Sony Xperia model numbers that have been leaked for a 2014 release, and a formal announcement for the devices is expected to be split between CES in January, and MWC in February.