Well...
In the original question, altitude is not a constraint, only attitude; neither is airspeed or power. While Old Smokey is correct for the immediate transient effect, I'm not sure what the final, stable result will be.
Seems to me that at constant attitude, AOA will depend on whether the airplane is climbing or descending in its final configuration... Constrain power as well, and added drag will determine airspeed and descent rate. At constant attitude, AOA will increase in a descent and decrease in a climb.
Add power and constrain airspeed, and the lift provided by flaps will cause the airplane to climb, decreasing AOA. With slats, lift available depends on whether the increase in camber offsets the decrease in AOA...