This sounds a lot like classic late 80's era Dokken. Don sounds very good here, despite the health problems he has had. Album release date is Oct. 27th. I will be very interested in auditioning this record.
What will be missing (I'll listen to them) is the personal connection to the music. Lithium (the song you quoted) is a very personal song about her own struggles, as are most of them.
There are apparently some songs she doesn't release, but has performed live, because they hurt to do and she has to be in the mood to do them and so she doesn't want a "commercial" version.
There are singers with more range than Amy (Floor Jansen and Sarah Brightman both come to mind) but there's an undeniable coupling of her music to her identity that makes any cover/tribute "less than". It's not the same as when Floor took Ghost Love Score, a song sung by Tarja, and reimaged it, because that song was written by Tuomas, not Tarja, it wasn't about or by her, so Floor could, and did, make it better, by simply being a better and more dynamic singer.