Unless they add more original, Thunder and Heartland material, then i'd say they are a tribute band. They follow directly in the footsteps of The Snakes, Company Of Snakes and M3, just minus Bernie Marsden. The first 2 both released 1 great album of new material, then a live album of Whitesnake covers. The third released 2 live albums of Whitesnake covers.
This new band play 90% Whitesnake live and started off as Micky Moody's Whitesnake, then Monsters Of British Rock and are now Snakecharmer.
Admittedly, they'll probably do it better than the current version of Whitesnake, but they still border that tribute band category, just as much as Giant, Hardline, Jimi Jamison's Survivor, etc and so on and so forth...
Niv