This is a great set of reading materials. It is great to find out how teams are building in resiliency at the micro level. That being said, I would never actually use this project for building things. IMHO: Libraries > Frameworks.
I also agree that libraries are preferable to frameworks and Hystrix is in fact just a java library that can be used as little or as much as one wishes.
It purposefully tries to have a small number of dependencies so should be easy to pull in without significant impact.
@benjchristensen