The removed maps will be Steppes of War, Delta Quadrant, Blistering Sands and one more that is not made known yet. Currently, five new maps are being tested and four of those will apparently take part of the revised new pool.
Aiur Garden:
Tal'Darim Altar:
Biohazard:
Crossfire:
Terminus Re:
The changes that will be agreed upon will come to be in the next GSL season, so the now ongoing one will finish with the map pool that is currently in operation.
Links
TeamLiquid.net - Source