Let's start with the bad.  So what's the worst-case scenario if HR analytics really catches on?  One could envision employers somehow using HR analytics to delve ever-more deeply into the private and work behaviors of employees (even knowing every little detail of their medical history and personal habits), and using that information to become more efficient in sorting out the wheat from the chaff.  Almost certainly there would be more than a few bad choices along the way.  Not a pretty picture. 

A more probable scenario is that employers will use HR analytics to continue to improve the efficiency of their hiring, succession planning, and  job design processes.  HR analytics would be applied primarily to wring out whatever vestiges of inefficiency may still remain in the workplace.  This could make workplaces less frustrating for the majority of employees.  Not a bad picture, but not terribly inspiring either.