If Google is successful, other carriers might have to respond. "But I don't expect them to start offering $20 cellular plans anytime soon," Gold said of the competitors.
Entner put it this way: "Google is trying to change the shape of the wireless industry with a relatively modest effort."
Potential losers and a laundry list of concerns
In addition to whether Project Fi can successfully transfer connections from Wi-Fi to cellular with its unnamed innovative technology, there are other concerns.
The first is coverage. Google won't even invite users to join Project Fi's Early Access Program if they live outside of network coverage areas.
Google's coverage map includes nearly all of the U.S., plus parts of Canada and Mexico. In the vast area west of Kansas, there is sparse LTE coverage and mostly 2G and some 3G cellular service. Montana is almost devoid of any coverage at all, at least for cellular. (But Google might have a trick up its sleeve with various low-altitude balloons or the use of low frequency spectrum.)
The plan also only works with the Nexus 6 smartphone. Google will eventually need to move beyond a single handset if Project Fi is expected to advance beyond the project phase.
"The impact of Project Fi will be minimal given the link to Nexus 6," Milanesi said. She noted that buying a Nexus 6 for $27 a month for two years, plus $30 a month for service and data, "doesn't sound bad on paper, but with the new plans from T-Mobile and AT&T, you have similar options with a broader choice of devices."
Still, it's clear that Google wants to test its Project Fi idea carefully. "In the beginning, when you launch something like this, it's important to limit the number of moving parts to be able to find out more quickly what the real problem is should trouble arise," Entner said.
By using a single device, it will be easier to introduce new "nifty" services and software. "They will come up with things we haven't thought of," Entner said.
However, Milanesi said if Google wants to move beyond the project phase, it will need other phone models to "show how serious Google is to make this a mass market service versus an experiment."
Another concern are the the Invites and Early Access. Even if a Google fan gets into the Early Access Program for Project Fi, it's possible that after a few years, Google could pull back and decide not to proceed. As with Google Glass, the wearable technology that may be resurrected someday, there could be a degree of uncertainty on the minds of many users.
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