Veeeery interesting
I mean, there were not one, but two "probably"s in that sentence, but I guess this means it's fair to exclude all the following from being the next historical game:
- WWI
- WWII
- Medieval III
- Prehistory
- Vikings (and obviously anything in Attila's time period)
- War of the Roses (and therefore any of Europe in Late Middle Ages?)
- American Civil War (so possibly no "Victoria" title?)
As art director, he will be pretty heavily immersed in concept art for the next historical, so it's very unlikely he'd name the game he's currently working on. So I'd say that is quite a reliable list of eliminations, all in all.
So, what does that leave, then? Renaissance is the big one, to my mind. Or China.