Hi,
There are a number of ANT devices on the market, including TI’s CC257x parts that are available that do not have additional licensing requirements associated with their use which are easily accessible. The CC2567 is one of the exceptions which unfortunately is not under our control. Also clarifying on earlier concerns, no "volume commitments" are necessary, but simply contact ANT Wireless directly.
ANT is an extremely lightweight, highly scalable, and flexible protocol meaning that a "stack" layer implementation between the hardware and the application is not required to enable advanced ANT functionality (auto shared channel, continuous scanning, etc). The commands to control ANT on a CC256x are virtually identical to a CC257x except for an HCI wrapper.
ANT protocol documentation, standardized file share protocol (ANT-FS)/compressed file format (FIT) designs, libraries, development tools, source code, device profiles, a certified device directory, etc are all available for free on the thisisant.com website.
Any developer is also free to create code or hardware which takes advantage of ANT and release it under any license they so choose.