Sega has filed a trademark for Total War Saga: Troy in the UK. The owner of the trademark is Creative Assembly Limited, developers of the Total War series. According to a reply from an official Creative Assembly account on Reddit, it appears that the new AAA game from Sega will not be related to the studio:

However, this trademark indicates that Creative Assembly and Sega could announce the new Total War game in the near future. Stay tuned at Final Weapon for more updates on Sega titles and Total War!