Between the Mavic Pro and the Spark you have all the bases covered. If I were to recommend you a third drone it would be the tello (for practice without GPS and indoor fun). I would be surprised if the Mavic Air was dropped entirely — one the Mavic Mini is out it doesn’t full any niche (expect specific price point).
Truth be told the recently rumored “Mavic Mini” may replace all three— so maybe wait a month until you see the next offering from DJI.