"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
Apple to Launch 4K 21.5-inch Retina iMac Next Week, iPad Pro in Early November
As has been previously rumored, the 21.5-inch iMac will have a resolution of 4096 x 2304. Code discovered in OS X El Capitan has pointed towards Broadwell chips with Intel Iris Pro Graphics 6200 and AMD Radeon M380 - M395X discrete graphics for the new iMacs.
Rumors have also suggested the new 21.5-inch iMac will include an improved display quality with greater color saturation, but the external design of the machine will remain the same. Due to the new Retina displays, the 21.5-inch iMac models will be priced higher than existing iMac models.
The 27-inch iMac is not likely to receive an update alongside the 21.5-inch iMac and it is not clear if Apple will also debut new rumored accessories alongside the machine. According to regulatory filings, Apple is working on a second-generation Magic Mouse and a new wireless keyboard with Bluetooth 4.2 connectivity and a rechargeable battery.
As for the iPad Pro, Japanese site Mac Otakara recently suggested the larger-screened tablet would launch in early November, a rumor that 9to5Mac concurs with in today's report.