Not if you keep in mind that he makes good money with the game and wants to keep doing so. And with that many side quests open I don't see any reason for the dev to stop developing the game. Therefore it just doesn't make any sense to think that it's end is near.You know: bring the main storyline to a satisfying conclusion
You really need to think far outside the box here to get anything else than what's in the sentence
He might create a second main story, but as explained, it would have to branch out from here.