ATSA staffing at Swanwick is already tight. With the present method of ops, a sector can not be opened without a dedicated ATSA. With ATSAs being so short it will not be long before sectors are not opened purely because of a shortage of ATSAs.
The aforementioned strategy will further reduce the ATSA compliment as student controllers will not be working in the A position for any significant period of time. This will almost certainly lead to sectors being closed; unless someone has a cunning plan to move away from the T, P and A concept.