After the Trae Young trade went down, the Hawks are still apparently pursuing Anthony Davis.
With McCollum and Kispert's contract's untradeable for the next few months, the Hawks would need to attach Porzingis and Kennard's expiring deals going the other way. Dante had a great year in the G League last year, hasn't had much playing time for the Hawks and is really there to make the money work. The Hawks give up a middling first rounder from this year's draft, which compared to their Milwaukee/Pelicans swap is seen as more expendable. This is all assuming that Atlanta is unwilling to trade Rishacher, which seems to be the case according to reports.
The Mavs get off Davis' long term contract for more immediate cap flexibility this summer and a first rounder to improve their younger talent moving forward.