After re-reading the original Bloomberg report, it only states that Apple disbanded the division that develops router. They extrapolated from that action that it mus be exiting the business. But it's very possible that router development will continue in a different division and that the action is just internal restructuring.
This is a fair point - just how much development does the Airport require at this point? Sure - some, and slap in a new chip every so often as standards develop. But it is a mature product - kind of like how iMacs are just getting speed bumps and updated internals these days. Not as much focus on hardware development.