A pure babyface is something that is hard to find these days. No matter how much WWE pushes one person, he ends up being polarizing at one point or the other. Zayn, on the other hand, has a different story.
He is impossible to hate and easy to love thanks to the underdog characteristics that he projects.
Zayn has been booked as an underdog ever since he made it to the main roster and this fact could be put to use if WWE pushes Zayn as the main event level baby face on Raw just like they did with Daniel Bryan.
There are a lot of buts and ifs but it is a practical idea on paper.