Since carriers have done away with contracts for their networks mean more phones that WILL USE both GSM/CDMA. Its not that hard to fathom actually. Its that much easier to switch to another carrier. I have a friend that works for Verizon and she said the 10 will be GSM/CDMA. Maybe Sprint/Verizon are still working out the contract details with HTC.
Sprint and HTC have a pretty solid relationship. HTC/Sprint push out Android updates faster than any other phone manufacturer and carrier.
The tech is in there, we're probably waiting for certificaiton from the carriers. From the unlocked version: 2G/2.5G - GSM/GPRS/EDGE, 850/900/1800/1900 MHz, CDMA: 800/1900 with EVDO Rev A, 3G UMTS, 850/AWS/900/1900/2100 MHz, 4G LTE (up to 450Mbps), FDD: Bands 1, 2, 3, 4, 5, 7, 12, 13, 17, 20, 28, 29, 30, Support Cat 9 LTE, download up to 450 Mbps, upload up to 50 Mbps