Unbundling is a phenomenon that consists of dividing an existing software artifact into smaller ones. It can happen for different reasons, one of them is the fact that applications tend to grow in functionalities and sometimes this can negatively influence the user experience. For example, mobile applications from well-known companies are being divided into simpler and more focused new ones. Despite its current importance, little is known or studied about unbundling or about how it relates to existing software engineering approaches, such as modularization. Consequently, recent cases point out that it has been performed unsystematically and arbitrarily. In this article, our main goal is to present this novel and relevant concept and its underlying challenges in the light of software engineering, also exemplifying it with recent cases. We relate unbundling to standard software modularization, presenting the new motivations behind it, the resulting problems, and drawing perspectives for future support in the area.