Product platforms are an approach of variant management which is widely used in industry. During the planning process of a platform portfolio, the scope for development of derivative products based on a platform is limited to some extent. In this paper, we address temporal aspects of a platform portfolio. The task during the planning process is to find an optimal compromise of the scheduling of products and platforms with their revisions. To gain a decision-making ability about the future platform portfolio, dynamic changes during the lifecycle of product platforms must be anticipated. That can be achieved by forecasting changes and variations of a company's context and within the own organization and to analyze its impact on the platform portfolio.