Most INFPs I've met over the age of 50 have been high-functioning & pretty cool all around. The ones who are less high functioning still function pretty well, but have had more turbulent life circumstances which I think has held them back (ie. divorce, ill children, etc).
As the age, INFPs get more comfortable in their own skin - aka confident in who they are. They get out of "Fi-Si" loops of lamenting what is & what has been & feeling doomed to never fulfilling potential. They use Ne more to connect inner ideals to potential ways those ideals can manifest. Basically - they get out more & DO more
.
As for emotions - MORE expressive. More comfortable with emotions & less needing to hide vulnerability. Less worry of invalidation - not needing to carefully have it all reasoned out in advance so as to make a defense, but knowing they can if necessary. The Te self-critic has been shushed. Te is just for organizing drawers now & paying bills on time. There is a security in the soundness of their ideals, stability with their identity (strip away shame), and sureness in their own abilities to do what they need to do.
To me, this is the positive Si - a stabilizing of one's own "place" in the world. They find their niche, calling, cause, whatever you want to call it. They have a grasp of "how it's done", although absent-mindedness and creative approaches are still there. It's more like a sureness they can figure it out as they go (confidence in Ne).
They assert their needs more clearly, are less apologetic about needing &/or, er, existing. They seem to know they have something to contribute that's of value to the world. Inspiring, motivating, healing to others. They're not motherly (even if moms)....they're like some cool aunt who is way more honest with you about life than your parents would ever dare to be. They know themselves so well, that by just being them they help others find who they are. I find this heartening, as that's more the person I would like to evolve into, as far as options go.
And the female INFPs are usually artfully and/or elegantly dressed. Sometimes kinda wacky too. I had an art professor who I am sure is INFP and she looked like Patti Smith
. She taught art (obviously), was a working artist with her stuff in galleries & with reviews in papers & stuff, was an animal rights activist, infused her students with enthusiasm for art, was very "motivating", but also had a grasp of negative realities without being bogged down in them. A lot of BALANCE basically. They basically find a way to communicate their value-concepts in ways that enrich their lives & the lives of others. They lead by example a lot, quietly.
And no, they don't look like ISTJs or ENFPs - they're possibly more readily identifiable as INFP. When I see the inferiors differentiated (or what I am calling that), they don't become equal in the mentality as the dom/aux. In fact, they almost seem to subside (stop trying to compete with the preferred functions..? feel less antagonistic...?), but appear to take on minor, supporting, positive roles in the person's mind. It's like, as the person is more conscious of this as a part of themselves & stops trying to repress it, they find a niche for it, so it's still subject to the dominant. I think this is the "balance" that results - NOT making people into one blob with no distinguishable preferences or personalities (which experience should teach us is not real).