A time limited obligation does makes sense. None of us know what's in the contract between Castle and RISC OS Ltd., but I believe that people have reported that it insists on sales for 'desktop' usage, whatever that means. Even it it does just mean non-embedded, x86 hardware is so ubiqutous that Windows does get used in borderline embedded systems.
Anyway, that's all water under the bridge now. Castle state they need RISC OS to acknowledge the breach of contract before they can issue new licenses, but that they *will* issue new licenses. It is a valid concern that without competition the terms may not be reasonable, but Castle need to goodwill of the community at the moment, and I'm quietly confident that this sort of shakeup is what was needed.