And you bet they will since the fee for debit MC/VS transactions will remain the same as current Maestro (fixed 0,05 - 0,10 cts). Where credit transactions cost between 1.75 %- 2.50 % of the payment total.
Btw, shops will not need to do anything to start accepting these Debit transactions as a replacement of Maestro, if they want to accept Credit transactions however they will need to take steps to start accepting these themselves.