I think we need a DESCENT karaoke game too.
And Harmomix is the master doing it. A karaoke game based on Rock Band engine would be awesome.
Lips and Karaoke Revolution are humilated compared just to "Vocals" feature on Rock Band. The voice recognition, system of scoring, harmonies, pitch corrector, etc.
HMX has everything to beat them with the best game ever. Besides, its just speculation.
But if its for dreaming, please let it be ROCK BAND 4!
Expert Vocals (plus accent)
For major interest, I think the trailer would need to open with an A7X song as they're one the most popular bands at the moment.
Wishlist (possible artists):
 The Killers
 The Cure
 Sum 41
 Linkin Park
 Green Day
 The Offspring
Witticus: "GeeNef speaks to me like schizophrenia, his words touch me where my priest could reach."