First off, while the Air is in no way upgradable (the processor, RAM, and storage are all crammed onto one mainboard, along with most of the other silicon), Apple's put a bit of thought to repairability.
For example, the external ports are on two separate logic boards, which means if you cause some damage by being careless, the repair should be a lot cheaper than it would be if you have to replace the mainboard. This is always a nice touch, especially as now the MacBook Air draws power from a USB-C port, and not the breakaway MagSafe connector.
The new MacBook Air also has a fan. While Apple has shifted to a fanless design for its other lightweight laptops, the new Intel Core i5 processor must output more heat than a fanless cooling system can cope with, and as such requires some airflow to get it out of the case and into the atmosphere.
Another nod to repairability is the stretch-release adhesive strips used to hold down the battery, which make removing the battery easier, and a whole lot safer since you don't have to go prying at it and risk rupturing the unit.
But there are some repair headaches too. Repairing a damaged trackpad will involve removing the mainboard, while damaging the keyboard will result in a full teardown since it's integrated into the top case.
Even replacing the battery will mean having to dig out the mainboard and speakers.
The bottom line is that the new MacBook Air is a little more repairable than some Macs, but that doesn't really mean that much. While it's a nice touch that the ports are modular, upgradability and repairability is clearly not a high priority for Apple.