Bill will have to answer if there is in fact a version 10 in the pipeline, but given the amount of time between version 8 and 9, I wouldn't hold my breath. And the major difference between 8 and 9, was the data supplied with the software. The program itself is being constantly upgraded - more often than not after suggestions made in this group - to the extent that the latest installment of version 8 and the initial version 9 was virtually identical.
Question is what you want a version 10 to offer that is not available in 9, or which may be offered through an upgraded version 9?
More than enough has been said about "realistic" vs. "uranographic", but what I think Guide could benefit from, is an upgrade of the user interface. Indeed, to long time users, the interface is Just Fine, but even though I have been using Guide for years, I still find it a bit awkward. At the very least, I'd welcome improved documentation on some of the features, like a comprehensive Alt-J list of commands.