Hi Calogero - I think you are right, that many of the _ideas_ of the Agile movement will live on. It is only that the Agile _movement_ seems to be in decline. A similar think happened with the "Lean Six-Sigma" movement: it evaporated very quickly, but to this day people use ideas from that movement.
I also think that "Agile" ideas are not quite right, so its decline is not just because of misuse: Agile is fundamentally flawed in many ways. For example, the Agile Manifesto says nothing about leadership, yet leadership is the most important thing of all.
The Manifesto's four values were written over a weekend, by six of the 17 people who attended that famous gathering at Snowbird (I hear that the rest were too busy skiing). It is no wonder that they missed the mark. But the values are pretty good. Some of the principles, which some of the guys added later, are quite wrong (self organizing teams, face-to-face communication), although the rest are okay. But the Manifesto is not based on research or any established theories of behavior. It was guesswork.
We need to move on. I advocate looking to what we have learned from research in organizational culture, behavioral psychology, leadership, cognitive science, and other relevant fields.