I would like to express my extreme displeasure that support for this hardware is no longer. While I understand time and technology marches on, this hardware is not all that old and would expect it's support to continue for some time yet.
One of the reasons I choose to go with National Instruments was a history of continued support for older hardware.
I'm sorry to hear that you're unhappy with NI dropping support for the 9172 chassis with the 17.6 version of DAQmx. National Instruments tries to prepare it's customer's for such events by sending End-of-Life Notices, so that our customers know how long a product will be available and how long we can offer support for it.
That being said, the End-of-Life Notice for the 9172 was sent in January 2010 and the software support was dropped in December 2017 (with the release of DAQmx 17.6), meaning the hardware was supported for almost eight years after being announced as EOL.
While both devices have received End-of-Life notices, National Instruments does still sell the USB-6009 in certain cases, and therefore has continued support for the device in the more recent drivers.