Re:The problem is that GIF never went away (Score 1)

One big reason is the PNG/MNG extension naming crazyness. People love using GIF both animated and static without needing to worry about the extension. There is a lot of code out there (ad serving) which assumes the extension won't need to change for animated vs static images, and this just adds one more thing to worry about. If the creators of PNG (as good as it is technically) had thought a little bit more about the end user and what would have been necessary to switch to their format (i.e. market research), they might have made things easier.