Update: Apple has discontinued the iPad Air lineup. On March 21, 2017 Apple released an entry level 9.7-inch iPad to replace the iPad Air 2. You can learn all about the 2017 iPad model here.
It is unknown at this time if and when Apple plans to update its iPad Air lineup, however, recent rumors have suggested that production of the next-generation 9.7-inch Apple tablet will begin in the second quarter of 2016. The same supply chain source has also hinted that the iPad Air 3 will ship with 4GB of RAM to support its new 4K display. If true, this will make the iPad Air 3 Apple's first 9-inch tablet with that much RAM. The first Apple tablet to ship with 4GB of RAM was the iPad Pro in 2015.