Why wont vanessa hudgens and zak efron be in high school musical 4 and 5?

Vanessa Hudgens and Zac Efron are unlikely to appear in "High School Musical 4" and "5" primarily because the storyline has shifted focus to a new generation of characters. Additionally, both actors have moved on to pursue different career paths and projects, making a return to the franchise less likely. Their absence allows for fresh narratives and new talent to emerge within the beloved franchise.