For the uninitiated, consequences include (for instance) not being able to use custom ROMs (such as CyanogenMod), as long as you wish to use any app that utilizes SafetyNet. Banking apps, Snapchat, Pokemon Go etc. (it's getting more and more widespread)
EDIT: Google product forums discussion https://productforums.google.com/forum/#!topic/nexus/mZAQzjt...