They haven't said anything about WS and OE. They have said that AE will scale based on base tax. A 3 BT province would give about the same AE as it does today. 1-2 would give less, 4+ more.
Those numbers are not something a paradox dev has said, just speculation.
Anyway, AE now scales to BT and WS costs have been tweaked. In particular the cost for province tradepower has been reduced, as the increased trade power values on ICoTs and estuaries made them a nightmare to conquer.