"High School Musical 4" has many fans are anticipating its premiere despite the casting issues faced by the upcoming movie. Fans are hoping for a reunion between the original cast members, but it is said to be impossible.

Because of personal concerns, the two lead stars of "High School Musical" will not be able to be part of the upcoming movie. Vanessa Hudgens and Zack Efron cannot star together in a single movie because of Hudgen's current boyfriend. 

Austin Butler and Vanessa Hudgens have been together since 2011. When Hudgens reportedly agreed to work with Zac Efron in the upcoming film, Butler turned into a green-eyed monster. As per iTechPost, having his girlfriend work with an ex-boyfriend, who wouldn't be enraged with jealousy. 

Furthermore, it is also said in a report that the two ex-lovers may have a hard time with their acting skills if working together. Despite having agreed to work together in "High School Musical 4," Zac and Vanessa did not foresee the effect it will have on Hudgen's current love interest. As a result, it is possible that Vanessa will be handing over her role as Gabriella Montez to singer-songwriter Taylor Swift.

Moreover, according to Billboard, the presence of the original cast members of "High School Musical" will be impossible to attain. It is worth mentioning that the nationwide casting search for "High School Musical 4" has already begun. 

With regard to the upcoming film's plot, it seems that Troy Bolton and Gabriella Montez will still be characters in "High School Musical 4." The two pioneers will be taking up the role of mentors to the new batch of musically talented students.

It is still possible to have Zac Efron play Troy, however Vanessa is unlikely to return. Fans may be seeing a Zac Efron-Taylor Swift duo in the upcoming "High School Musical 4." Can Taylor Swift fill in the big shoes left by Vanessa Hudgens?