It is a common tradition to see stars from Mollywood doing cameos in another language and sometimes that has been working. But most of the times it is not bringing much success.
However, directors like Siddhique mention that when an actor grows in presence, it is natural for him to try out his presence in other languages and reach wider audience.
So far, the likes of Mammootty, Mohanlal, Suresh Gopi, Manoj Jayan, Prithviraj and others have dabbled with other languages. It is only Kunchacko Boban who has not ventured elsewhere.