Shutting down zones wont be required, getting support of community heads and zone owners to advertise and aid migration will be needed. It can be made to happen, especially if zone owners and ops are offered roles in the new game. However politics could be a road block. There are always those who want to cling to their positions or force their way into a position of power. Nevertheless IF the new client begins to draw enough people over, the flood will eventually be unstoppable. I would like to hope that it can be done smoothly as a united community, but only time will tell.