Here is an at-the-time writeup of the unit in question: https://www.wired.com/2012/02/wd-my-book-live-duo/

WD sells the hardware, hard drive, and software as one sealed unit. The part that fails first will be the hard drive inside. The unit shouldn't be end-of-life until it actually should be expected to fail. (WD claims the units were end of life in 2016)