And I'm predicting that it will be economically impossible to handle future data demand, if you allow "unlimited data."

Even with the best intentions. You would need to be subsidized by the government to provide it.

Since so few people TODAY currently make use of their unlimited data, the network can afford to offer those terms. And they found that by offering those terms, they attracted a disproportionate number of customers. In short, it was popular and profitable.

But at some point, the aggregate network demand will exceed even the THEORETICAL network capacity, if you offer your customers unlimited data, and demand goes up the way I think it will.

Or in essence, you will need to limit bandwidth to the point that calling it "unlimited" is just ridiculous.

> But at some point, the aggregate network demand will exceed even the THEORETICAL network capacity, if you offer your customers unlimited data, and demand goes up the way I think it will.

At which point you build out the network so that it can handle the increased demand. The problem of congestion doesn't magically go away if you ditch unlimited plans for pay-per-gigabyte plans.

Even barring that, the wired broadband world already addresses this by making speed the useful commodity instead of quantity, and there's very little reason why the wireless world couldn't do the same. "Our networks are getting congested, so we're going to switch to a new model where you can pay cheap rates for 2G speed or pay more for 4G speed or pay something in between for 3G speed or pay top-dollar for our newfangled 5G" is a much better answer than "our networks are getting congested, so we're going to just cap users' usage of it and hope the problem goes away".

That, in short, is what Google Fi should be doing. That would be an actually-compelling reason to switch to it instead of T-Mobile.

Until then, T-Mobile will continue to get my business, and T-Mobile will therefore be at least that much more incentivized to provide unlimited data plans.