Vendors are wary to the point of being phobic about FOSS and surrendering control to users. See the debacle with the locked bootloaders and software blobs on android handset manufacturers. Factor in the almost mccarthy-esque paranoia about tech secrets and patents, and I find it very hard to believe that a true FOSS OS (meaning truly GPL 3 compliant) would be viable in today's market. The big players would probably not even touch it.