You are living in a dream world. Management wants three things:

1) control of the people doing the work,

2) perfect predictability for all aspects of the work, and

3) constant reduction in the amount of (calendar) time and resources needed to do the work.

Scrum/agile provides none of these. (I doubt the last two can ever be obtained by any methodology.) I see no way that managers in large or even medium size companies will ever give up the first one. After all that is what they are paid to do.

Scrum/agile is the "flavor of the month" promoted by consultants who make big bucks from touting it. In time it will be superseded by some other methodology which will be promoted by another group of consultants who will make big bucks from touting it.

The basic fact is that at the present time software development is a craft rather than an engineering discipline. Success depends almost entirely on the skill, knowledge, experience, and motivation of the people doing the work. No methodology is going to change that. And no methodology is going to provide management with what they truly want.