If I were google, I would want to deploy to the more dense places (that could afford the service).
South Austin seems to be the more "hip" place to live, and I think people in their 20-35 age range would be more likely to want to jump on Google Fiber. I could be totally wrong, but it's just a guess.
Austinite here. East of I35 is commonly known as the "wrong side of the tracks". If Austin is wiring up for business and residential focus, they'll do west, some limited up north, downtown, and down Congress Avenue & First Avenue. They might extend to the west of MoPac (Loop 1, follows the old Missouri-Pacific line) but I'm not sure that the neighborhoods there are officially part of Austin or incorporated as a small suburb community.
Your parent comment said the hipster parts of east Austin, so we're not talking about rundberg and the areas that the cops are swearing they'll clean up. There are parts of the east side that are friendly and cheap. There's a nice pocket of neighborhoods around 51st street that's low on crime and just a long bike ride from downtown.
Mueller and on down through 2nd Street out to about Chicon east of 35 (an a bit beyond) is full of 20-30 something professionals. It will likely see some action. Maybe Riverside because of the college students but I kinda doubt it. Zilker, SoCo, and Travis Heights have a good shot down south. All of the neighborhoods around downtown and UT are almost certain to see it first. I gotta believe from there they'd just work their way up Burnet, Guadalupe and Lamar until they hit 183 (Though that process make take five years). Tarrytown up to Far West on the West side of Mopac is a pretty good bet too.
Notable neighborhoods that might be out of luck for awhile: WestLake...too far out, too spread apart. South East from Oltorf on down is probably not going to see it for a while. South Lamar is probably a no go (not enough residences or tech businesses) and so Westgate and Manchaca on South and West (Circle C and environs) are probably out of luck too. The Arboretum area might get lucky but I doubt it and I think further west and north of that is pretty unlikely in the next few years unless Google is happy having disparate clusters. I think that area would lap it up but I don't think it is close enough to the downtown/UT epicenter where this is likely to spread from.
If I were Google, I'd pick three different clusters to spread and meet. One at UT/downtown to spread in all directions but particularly North, one at the Arboretum to spread West and North and one somewhere around Westgate to spread West, East and South.
East of I35 hasn't really been known as the "wrong side of the tracks" for several years now. It's changed tremendously since what it was like in the late 1990s/early 2000s.
I work with what I know. Sorry for the misidentification. Some friends of mine just north of Lady Bird Lake had their door kicked in a few months back by a few neighborhood kids. My opinion of the area was informed by old history and that incident.
Why is that?