I'm 37 and have found the same. I'm just not as self-destructive now as I was for a while when I was younger. Having a son helps with that. When I'm not strong enough to stay calm for myself, I can do it for him. I haven't cut since I was a teenager and not overly out of control with that.
Soft drugs instead of hard drugs, unlike my 20 year old self. Promiscuity with a select group of partners only, don't ask about 3-4 years ago - that was excessive. Not getting extremely drunk as often - I'm talking to you, recurring problem that shows up every couple of years.
The thing that's gotten worse is that my temper is shorter. But on the flip side, it's not quite as strong either. Sometimes I go through a rough time where I can't control the mood swings, but that's when I get help and take anti-depressants for a while. It drops the peaks enough that I can grab ahold of them easier.

I think that if the "cure" for borderline personality disorder is doing that skills-based treatment, we're on the path for the natural version of that. Every year, we get a little better at some of our struggles because our personal growth kicks in and makes us smarter by experience. So, by learning these skills via trial and error through life, we're getting the same treatment, just very slow. My six cents.