Premise No. 1: The world of teaching has to change — and is slowly changing. Despite the harsh attacks on the profession by too many shrill voices, others are working to improve pay and working conditions. When these changes take effect, the exodus from the profession will slow down.
Who is working to improve pay and working conditions? Unions? Somebody else?
If the economy doesn't improve, there will be no improvement in pay and working conditions. However, if the economy ever really improves and people currently teaching suddenly have options, then we may find out what an exodus from teaching really looks like.