It'll take generations for Gazans to not be angry. I mean, they're still angry about the Nakba, so I can't imagine this will fade any faster.
For the record, I wasn't thinking so much of Nazis when I was talking about nations that have done worse. I'm thinking about incidents like Serbia and Srebrenica and the Rwandan Tutsi genocide. Neither Serbia nor Rwanda are international pariahs at the moment, though they were 25 years ago. Not everyone has welcomed those countries back to the international community with open arms. Not everyone forgives & forgets. But by and large the world just marks those as incidents in the past, and Israel may expect that.