Here we go again...this is nothing new.  Every 10 years or so this is brought up and, despite all the verbiage from the DDS's, it basically boils down to lowering the standard of care for the same price.  Do you actually think that the fees for prophys will be reduced?  It takes a minimum of 480 hours of supervised hands-on instruction in instrumentation to become an RDH.  Who will be training the DAII?  I hope it won't be the dentists as the majority of the general dentists are woefully lacking in their scaling skills.  The dentists that are 50+ don't even pick up a probe. 

Just because you look in someone's mouth and it looks beautiful, doesn't mean that there aren't deposits subgingivally or pockets that need extra attention.  A patient can present looking the picture of health at one appointment and six months later come back and have gingivitis.

You do not handle the shortage of hygienists by reducing the standard of care.  Why would someone want to invest in an education to become an RDH when every ten years or so their career is threatened.  There is also a shortage of dental assistants...who will they be replaced with?  The DDS's that are proposing this are shooting themselves in the foot. 

I agree with Dr Bill Malone DDS who said "An insane request by whomever is proposing this."