If Google wanted to come at Comcast, they'd be gearing up a lot faster than they are. At this point Google Fiber is mostly FttPR-Fiber to the Press Release. And also, I don't think any of the first several Google Fiber locations were even in Comcast territory. So far AT&T and TWC have been their competitors.
They want to create demand because Google loves remote computing and loves internet consumption.
Google is providing a model for the ISPs by forcing local communities to deregulate their ISP franchising system. Before Google Fiber, each town or state would take a pound of flesh from the new company trying to lay down a network. Google made the cities bend over backwards.