Their design and tech couldn't keep up with the increasing demands on wireless routers. Apple's tech became outdated over time, and they didn't want to continue buying and updating outdated products because it would be a waste of resources. If you already have an AirPort router, you can keep using it, but you won't be able to connect any additional Apple products to it. The router will remain functional for both Mac and Windows devices, but Apple devices won't be able to connect to it.