much of what is currently contributed by HR staffs falls in the category of “complicated work” which is increasingly a candidate for outsourcing

Not only outsourcing, but increasingly rules-based (counter to a 'flow' environment of talent) which can lead to automation or DIY.

HR in internal coaching and development roles has a long and I think patchy history; outsiders often have more influence exactly because they are outside the often-more-formal internal environment of the organization. And so .. between providers of policy-based support services and strategic coaches / change agents with real influence, what space is left for HR to provide tangible value (beyond basic rules and hygiene) in the internally-and-externally connected workspaces of today ?

Thorny question ..