You cannot just re-assign…

You cannot just re-assign land to be a greenbelt. These greenbelts are protected because of their location and the ecological services they provide to the human inhabitants nearby. These include recharging of underground aquifers - the land must be maintained as wild lands so that the filtration of water into these aquifers is maintained and protected to prevent toxins and imbalance of chemicals getting into the water source that we as huge water consumers rely on. If you change or destroy the lands that provide the filtration (soil, rock layers, trees and plants that remove toxins etc) then the water will deteriorate. If you move these - down the line you will just reassign again. - we can't trust you to hold up previous agreements. Wanting to change this greenbelt proves it.
Moving or reassigning land to green belts is ridiculous - it's like cutting the rain forest down and saying 'oh we'll leave this other (unfertile) land untouched and the rainforest can grow there - rainforests took 100's of years to get to the point they are at. It may not be as obvious but the green belts are just as vital and cannot be 'moved' and expected to have the same function.
I feel that the powers making these decisions are looking to what money they can make - putting so many houses in the Golden horseshoe goes against any planning municipalities for property protection in the event of extreme climate changes - flooding, erosion, insecure foundations etc. Construction would have to shore up the foundations which would completely remove the needed protections from nature and the natural cycles that help us cope.
These changes would remove the Resilience we need for making our world sustainable in a changing environment. It is very shortsighted!! Build in areas farther north - promote business/economy in those areas. Stop focusing on the Horseshoe it needs protection not destruction.