Maybe another century or probably when the humans become extinct, I don't think that we're going to lose our dependence on fiat, Romans and other ancient civilization used a form of fiat currency and they all collapsed as a civilization and here we are still using the same thing.
But for me its always alive because theres a different uses to us in online and offline transactions. I agree with you that can only be a maybe. We know that every government need fiat thats why they are still exist. For author thats why there are more stable coins like usdt , busd and many more is because they need to control there assets to avoid big losses. Thats why they need to use this kind of fiat based coins.