I'm going through this on a smaller scale and have been evolving through my responsibilities for around three years.
I started as the only engineer with total control over a next generation system for a client, then for the last year and a half I have been making the painful transition from solving problems myself to trusting others to solve them.
I've grown a small team from nothing to three highly reliable members by doing much of what you suggest and following similar themes.
My responsibilities have been partitioned among them, group methods and practices have developed between us all, and finally, there is a capable group of people to carry on and evolve my hard work, which is now becoming their hard work. One of the best parts is that they actually produce higher quality work than I do, because I create buffers from business pressure and give them longer runways, so there is more time for attention to detail.
I'm in the process of handing over my duty as team lead to one of them and I'm pushing my way into helping our CTO with product design (and essentially anything else that comes up), where I hope to leverage my understanding of our various teams and business context.
I am evolving my role for the third or forth time by now, and I am doing it out of necessity, because, every hour of my time typically goes toward controlling dozens of hours of other people's time and so without an engaging task like writing code, my days feel endless, because there isn't that much I can do at any given moment. Jumping into my teams code and working on requests directly is actually one of the more self destructive things I can get into lately.
Therefore, I find product design highly engaging, it makes the hours fly (almost as good as writing code) and am sending the message that I'm here to help at a higher level than I ever have previously - apart from growing half of the environment for three years.
I don't even want a career by the way, I'm a remote 1099 freelancer if you can believe it. We have a really interesting team composed entirely of freelancers, but we seem to stick together.