I believe they were intending to use a 3.2 degree approach in addition to the displaced threshold to reduce noise disturbance. The summary document includes an estimated noise profile chart. I certainly remember reading that 747's and the like would not be allowed at Heathrow by the time the third runway, if approved, was built.
Yes, the revised proposal contains the following assumption:
"all approaches will be steeper than today at 3.2 degrees in 2030 and 3.5 degrees in 2040".