"...call and say they will no longer do pre-screening and all of the other aspects of hiring."

Hmmm, we already do much of that ourselves. OK, some of it. Seems HR is going to focus more on "sourcing" for awhile. It is possible to do our own sourcing - I get a feed of resumes submitted to the website, pop the ones I like into tracking system and ask HR to make appts for screeing.