This thread turned into something fabulous to read! Lots of great insight and thoughts. Most of what I was thinking has been covered already. I'm not fully sold on the gray hair as a catalyst for all of this; as Angie mentioned you've been headed this way for quite a while now! It's not like you've been wanting to adopt trends but haven't due to age or fear or anything like that. To me your search has always been about authenticity (mine, too).
Some thoughts, one a paragraph:
There's nothing wrong with splitting your wardrobe. I know lots of books and websites and stylists always list many "work to weekend" pieces, but your work and your weekend just don't overlap in the right way, there's too much contrast there. In addition, your work needs a certain level of conventionalism which you don't necessarily aspire to one way or another with your casual wear. AND you do loads of outdoorsy active stuff that requires actual gear. To try and reconcile all of those with shared-across-uses pieces makes no sense to me. It is what it is! To my mind, actually separating these two overarching wardrobes of yours, work and weekend, even if there are pieces that could be overlapped, is a fantastic approach. You end up with simplicity in getting dressed for both work and weekend, with the ability to "play" only if you feel like it.
I don't quite agree with the thought of you no longer experimenting. You DO experiment, you just don't necessarily bring in every single new/fringe trend and try to make it work. That's fine too.
On a semi-related note, to me it sounds like you are willing to give
most of your wardrobe time to the shopping part. Find the right pieces.
Then when getting dressed you can sort of auto-pilot but still know that
you'll end up with something fab.
I haven't been wearing my shirts much either, except for my silk button-ups! However I am starting to wear them untucked or fully tucked, instead of semi-tucked, for a cleaner line and neater, breezier look. I would be inclined to set aside your pretty silk shirts, especially if the prints/colors are favorites; you may go back to them in a year or two. Or perhaps once you have your wardrobe more sorted you'll have a better idea of where they can fit within it.
Hair is definitely an accessory (mine is my most important accessory along with my skin). When hair changes it does require a little tweaking everywhere else to feel right and balanced again.
Edgy doesn't mean black. I have 100% confidence that you can work color
in a way that feels authentic to you. You already do this
Having the major style stuff further refined will let you play with your shadow personas a bit more, if you feel like doing so.
And lastly, I think it is entirely possible to pare down the more busy style elements you previously identified with into a simpler frame. I have been working towards this myself the past few years. Minimally Maximal, as Angie has put it. "Clean Edge" is certainly something you can get to.
(As an aside, I showed my husband the Eva Longoria photos and he didn't buy into the makeup thing as presented. Said the only way to really judge the difference would be to have the same photographer, with the same setup, with the same angles, within a reasonable time frame. He also preferred the full face make up look; which I found really interesting as he doesn't really like that on me but said he liked it better on her.)