But it's Shimano. They're not just gonna tack on another cog, I'd say. Of course, they're gonna need new rear hubs as well, but I can't see them just flopping out cassettes and hubs and a firmware update - that would look like a total me-too catch-up move...
I'd expect an accompanying cosmetic change and at least one or two other refinements to justify a 9200 model number.