The government's overall objective is to reduce total net immigration to the UK 'from the hundreds of thousands to the tens of thousands'. Net immigration via routes over which the government does have control, including student migration from outside the EEA, will have to be cut by substantially more than half in order to meet this overall objective.
Data on compliance in the student visa system is limited, but suggests that rates of non-compliance are relatively low. Given this, it is clear that cuts of the magnitude sought by the government will not be achieved simply by stamping out abuse. Indeed, even stopping all student migration for courses below degree level would not reduce the total numbers sufficiently to meet the government's overall objective.
There is a risk that the proposed changes in the student visa regime impose substantial (and very real) costs on the education sector and the wider economy simply in order to deliver largely illusory reductions in migration statistics.