Seems like a reasonable assumption to me. I doubt they pay a flat rate to all providers they borrow from with Google charging by the 100 MB.

Google consistently tries to increase competition and make both hardware and network owners into a commodity.

Meanwhile hardware and network owners madly fight to stay relevant, like the aggressive customization of Samsung's android Touchwiz or the various telecoms lobbying against net neutrality.

I don't think that t-mobile and sprint are opposed to commoditization. The expansion of the commoditization of mobile access gives them new ways to compete against at&t and verizon.

The era of multi-year contracts and heavy device subsidies has primarily helped those with large market share maintain it. T-mobile in particular has been pushing to change how the market works and bring an end to some of the ways that customers have been locked in to carriers. I wouldn't be to surprised to seem them support further commoditization.

Even then a good strategy for the networks would be to build capacity on crowded areas where infrastructure is cheap and neglect all other areas for the second carrier.