I am shocked at how many different DIY versions of a smartmirror has been posted here in HN. I was hoping someone would kickstart something like this, but just saw https://www.kickstarter.com/projects/338193274/mirro-the-wor... didn't really get off the ground. Maybe you can kickstart yours and I can be the first to buy :)
It's probably waiting for the mass production of either e-ink display or screen as flat as a tablet to be more attractive and/or low power demanding.
I'm not attracted by the business side of things, but you go for it ! :)
I considered doing a kickstarter for mine. There have been 3 that I could find on kickstarter. Most fail for the same reasons... they try to do too much, don't do it well, and don't have a compelling use case.