Here's why:
* No official announcements: SEGA has not announced any plans for a Sonic the Hedgehog 4 Episode 3.
* Mixed reception: The previous two episodes, Sonic the Hedgehog 4: Episode I and Episode II, received mixed reviews from fans and critics. Some praised the game's retro style and gameplay, while others found it to be a pale imitation of the classic Sonic games.
* Sonic Frontiers: SEGA is currently focusing on the new Sonic Frontiers game, which is a major departure from the classic Sonic formula. This suggests that the company is moving in a different direction for the franchise.
While it's not impossible that SEGA could revisit the Sonic 4 concept in the future, it's unlikely to happen anytime soon.