That is exactly what he said, 3 congregations per building.
What's the significance of that?
My wife has been attending a small kingdom hall for 20 years that accommodates at least four congregations. It's at full capacity; there's no way to squeeze any more congregations unless you reduce meetings days to just one per week. I don't think the number of congregations per hall solves anything. It's the size of the congregations that will help their financial problem. Out of two halls, they may sell one and keep the other, but build it bigger to fit larger congregations.