But if you want higher specs and Retina display they already have the 13” MBP, and it starts at $1,299, same as 12” MacBook.
The real issue is how to update the MBA and keep it at $999. I don’t think that happens by introducing a 13” version of the $1,299 12” MacBook, or cutting $300 off the price of the current $1,299 13” MBP.
At a $999 price point, it’s going to be 8GB/128GB, with expensive upgrades from the base config. Maybe no upgrade to 16GB at all for segmentation purposes. There could be a display better than the current 1440x900 TN panel, short of the 2560x1600 IPS retina panel. But I’d hate to see them use a 1920x1080 (16:9) display, and 13” IPS @ 1920x1200 (16:10) doesn’t seem to exist.
I’d expect port changes; maybe 2 USB-C 3.1 without Thunderbolt, no MagSafe because charging is done through a USB-C port, likely no SDXC because it’s little-used now (and even moreso in the future) and can be supported with a simple adapter. Probably the butterfly keyboard. Built to take the wear and tear of being tossed into a backpack every day.