Perhaps this question is based upon a misguided assumption about performance. Nevertheless, say a corporate dashboard is being built and performance is a concern. Breaking the corporate model into functional models may improve query response time. Does Power BI support multiple data models?
Its been a while since we have connected in the forums! Here is a thought: If the models were contained in different Excel files and then imported the data model of each workbook into Power BI Desktop, that would work. You would probably have to work out details of refreshing.