Comcast/Xfinity now offers gigabit home internet for many metropolitan cities and expanding daily. Recently, I switched to their new Gigabit home internet and finally upgraded to gigabit download speeds.
Advertised speeds are 1000Mbps down and 35Mbps up. Wifi will be much slower since your wireless technology still can’t realistically go up above around 300-400Mbps. To take advantage, you will most likely need to hook up your devices via ethernet to get the full gigabit download speeds. Of course, in a few years, wireless technology will be much better and we may be able to actually get gigabit speeds on WiFi also. But for right now, if you need the fastest speeds for WiFi, you may be better off getting slower service.