Are Tatum and Brown untouchable in trades? Grousbeck explains

The Boston Celtics have plenty of work to do this offseason, but they at least have two pillars to build around in Jayson Tatum and Jaylen Brown. The question is, with Celtics co-owner Wyc Grousbeck acknowledging more roster changes to come this summer, is it possible either of those All-Stars will be moved?