Something you may not have considered...
Yes, younger coders/admins/etc are willing to put in insane hours, and can bang out huge swaths of effort.
The problem arises when you realize that most of the kids are not so adept at, well, solving problems that arise. As a corollary, that lack of experience is a basis for lack of creativity. They only know what they were taught with perhaps a few limited ideas, and haven't enough hands-on time in the real world to realize that there are multiple ways to get something done, especially on a macro scale - many of those ways being far more efficient and elegant than what they just barely learned in school.
Oh, and I have found that the kids by and large have little-to-no people skills. At all. In a company larger than 400-500 people, the ability to explain and persuade becomes just as important as the ability to do your job.
The good news is this: over time, those kids get that experience, those skills, and most of them realize that there is more to life than throwing 80+ hours a week at a project.
So let's tie it all together: As the near-median mid-40's guy, I've found that I don't have to toss my life upon the altar of the Kanban board. Instead, I find ways of getting the work done more efficiently, and have the people skills to demand (and get) management to set realistic timelines to meet the company's goals (meanwhile, the kids just bitch, moan, then go blast out 80+ hour work-weeks to meet the deadline, often at cross-purposes which blows the timeline anyway - then someone else has to go back in and refactor their barely-running shit, usually after release).
...and that my friend, is what an old fucker brings to the table. ;)