This would be a game changer for me if this were implemented in, say, a MacBook Air. It also might actually get me to sell my MacBook Pro in favor of something a bit more portable.
Update: This was a game changer for me, and I bought one.
Source: Photos of Likely 802.11ac 'Gigabit Wi-Fi' Card From Next-Generation iMac Surface - Mac Rumors and Next Mac ‘Gigabit Wifi’ spotted? Broadcom BCM94360CD PCI-E mini WLAN+Bluetooth card in the wild - 9to5Mac