The Celts should of course try to have cap space available to chase top free agents when they are available, but they also need to be aware of reality. Giannis has stated clearly that he intends to stay in Milwaukee. We all know that things can change and the Celts can't assume anything, but there is no reason to think that Giannis is leaving the Bucks. Getting Giannis can't be the plan, they need to prepare in case things change and he becomes unhappy, but by far the most likely thing is that he stays.