SOLVED On a hunch, I suspected that my installation of the Cisco VPN Client ( My version is 5.0.07.0440) could be causing problems. I tried uninstalling it, which failed in Windows 10. I rolled back my Windows 10 install to Windows 8.1, successfully completed the uninstall of the Cisco VPN client, and reinstalled Windows 10 and I have networking capability in Windows 10 now. 
XPS 13 (9343) Dell Wireless (Broadcom) 1560 Dell Wireless 1560 802.11c shows up in Device Manager as "working properly". Driver version 6.30.223.262 In Network and Sharing Center when I go to set up a new connection Windows tells me that "Windows could not detect any networking hardware." I have a shiny new Ultrabook here that's dead in the water. Any quick fixes for this, or do I need to downgrade it back to Windows 8.1?
No Networking Hardware Available after Windows 10 Upgrade