Even $100,000 would kill it. If 1 sat (or even 100 sat) == $1 then the fees would grind the system to a halt. The fees would be so high relative to the amount sent, that it wouldn't be worth it. From an investment perspective 1 sat==1$ is a nice round number. From a users perspective, only being able to buy things divisible by 1$ is crap.
Why would that kill Bitcoin?
I find it a perfect scenario to make Bitcoin as a digital asset that people will store value in it. The same as Gold is right now.
You just have to see it from another perspective. There are many use cases that bitcoin can cover.