Both GSM and CDMA are going away. T-Mobile is a mostly-LTE carrier already. Both Sprint and T-Mobile use LTE and most Sprint customers will already have compat

Both GSM and CDMA are going away. T-Mobile is a mostly-LTE carrier already. Both Sprint and T-Mobile use LTE and most Sprint customers will already have compatible handsets. Others will be given upgrade offers. T-Mobile’s network will form the core of the new network because it’s significantly better, most Sprint devices will support GSM and UMTS 2G/3G standards (while the opposite isn’t true), T-Mobile’s network supports voice over LTE, T-Mobile’s network has significantly more cell sites, etc. Some Sprint sites will be added to the network and Sprint’s spectrum will be as well. Other sites will be divested to Dish. The CDMA vs GSM divide just isn’t that important today given that carriers should be mostly LTE already.