10k+ miles on conventional lube. I love it! Welcome to the world of today's possibilities from current lubes and equipment!
This lube did everything right and nothing wrong. There is still life left in that load, but I understand folks are scared to tread out only so far. So as far as "safe" limits, 10k miles still leaves you a margin of safety. Whomever states that 3k or 5k miles is "cheap insurance" is stuck in yester-year.
The topic of TBN is only part of the story; you need to know TAN. TBN can be low, but as long as TAN is not high, you have no worries. TAN can even cross over TBN, but the lube can still be viable for some period of time. You really need to know both before you're at a point of knowning about condemnation.
Greatly extended dino OCIs are only for we heretics. With the next UOA, get TAN as well, and I suspect you'll see that you can go even further.
Your UOA is a great showing and you can take pride that you are bucking the old trends, and establishing new ones, with proof that you are still caring for your vehicle well.