I think a county version of Rocksmith would be very cool (It would be nice to have both kinds, Country and Western). Country music has a very large audience. There is a lot of cool guitar and techniques in country music. Especially these days where some of it sounds a lot like rock music (except the vocals). I would really like to learn some of the older stuff from Johnny Cash, etc... While we're rolling back the clock, some 50's would be cool. Chuck Berry, Buddy Holly, Ritchie Valens. Some blues would be cool too! Man, this could go on forever!
Variations in the visual theme of the game would add to immersion in game. That's one of the things I find interesting about Bandfuse's use of videos. It may take you more into the experience of the song it's self. Take you away from the note highway, watching your fingers, etc... One of the reasons in Rocksmith I don't use rehearse anymore. I play at a venue to play the full song. Just seems to broaden the whole experience for me.
No country needs it's own game, I don't even want to hear the snippets of it as I scroll through the songs.
I think that it depends really. Radio country would be really boring and unlistenable for guitar (except some brad paisley). Very guitar oriented country would be too discouraging to almost all rocksmith players.
They had some Johnny Cash in pro mode for Rockband 3 and I really enjoyed those songs. I'd be happy for a set of country releases... but yeah, if you go with some of the more guitar oriented stuff, it'll destroy you as much as any metal.