The T-Mobile’s Chief Technology Officer, Neville Ray, has stated that the company will be "approaching Gigabyte speeds" by next year. He carefully used these words as Cat 16 downlink that you saw with Snapdragon X16 standalone modem and that is now part of Snapdragon 835 in a gigabit class modem.
The Cat 16 standard supports up to 980 Mbps but with custom compressions, Qualcomm is one of the companies which can get it closer to 1Gbps in some ideal cases.
T-Mobile is using two technologies in order to reach 1Gbps. One is called 4x4 MIMO, Multiple Input Multiple Output and Samsung Galaxy S7 and S7 Edge are the two prominent phones which support this. The company released an OTA update in September enabling MIMO.
The second piece of the puzzle is called 256 QAM (Quadrature Amplitude Management) that supports the download and 64 QAM that speeds up the upload. QAM is used for Wi-Fi signals and does a great job.
The CTO has confirmed that there will be multiple devices in 2017 to support MIMO and one of the unfortunate developments for MIMO is that the Galaxy Note 7 was canned. That device supported 4x4 MIMO too.
We expect that many other companies plan to support 1Gbps speeds in USA and the rest of the world. This seems to be the direction that will be the following step after many companies started using Carrier Aggregation that is enabling providers to 300 Mbps download and 100 Mbps upload. Speeds approaching 1Gbps will be normal after 2017.