There's no doubt about it, we are currently in the midst of a price war in the US wireless industry. One could argue that T-Mobile started it when they dropped contracts back in early 2013. However when Sprint got their new CEO, Marcelo Claure, he decided that Sprint's network was not worth what they were charging, and immediately dropped them. While true in some areas, this is also when the pricing war really got started. While T-Mobile and Sprint are the smaller two carriers in the US, they have been putting pressure on the larger two, which T-Mobile CEO John Legere calls "the Duopoly" in Verizon and AT&T.
In 2010, AT&T got rid of unlimited data (although they brought it back recently, only if you sign up or are a customer of DIRECTV or their U-verse service). Verizon killed off unlimited data in 2012, they have not yet brought it back and they don't plan too. Sprint and T-Mobile do still offer unlimited data, as well as other plans which are cheaper and technically offer "unlimited data" but speeds are reduced after you hit your data cap. T-Mobile currently offers their truly unlimited plan for $95 per month. Which has been targeted lately by AT&T's prepaid brand, Cricket. After T-Mobile's earnings last week, the company's management spoke with analysts, including Jefferies analysts. Who stated in a research note that "management is very comfortable with its current position and does not view itself as a price discounter." Adding that they are content with their current pricing for their plans. Jefferies also noted that the "Uncarrier" announcements don't often change pricing, so we likely won't see them go up or down with future Uncarrier moves.
When it comes to unlimited data on T-Mobile, the question "do we really need unlimited?" often pops up. Due to their Binge On and Music Freedom programs that they launched as Uncarrier moves lately. Each whitelist video and music data from select apps and services so that it doesn't count against your data. However, the company's COO Mike Sievert did also state that they are "proud to be able to offer unlimited [data]". Sievert continued on during the earnings call by saying that T-Mobile "has the capacity and we don't have any plans to change the fact that we offer unlimited." Sievert also mentioned something interesting during the call, is that unlimited customers are keeping Binge On turned on, even though they have unlimited data. As they are finding it keeps videos from buffering - since it is using less data and a lower resolution.