The 33-year-old Pietersen, who scored 3 and 6 in Sydney, and 31-year-old wicketkeeper Matt Prior have been identified as possible victims of a post-series overhaul. Flower was directly asked about Pietersen but wouldn't speculate on his future.
The South Africa-born Pietersen has played 104 tests and scored 8,181 runs at an average of 47.28, ranking him behind only former test captains Graham Gooch (8,900), Alec Stewart (8,463), and David Gower (8,231) in England's list of test scorers.
"This will be a new start, and so it should be," Flower said. "It does feel like the end of some type of era.
"We might have to take a little more pain before we have sustained success again. And we might have to ask for a little patience in that regard over the coming months."