Chance the Rapper -
http://chanceraps.com/tour/
It would honestly be crazy if he didn't end up doing the SB within the next few years. Upbeat, accessible, while appealing to a much younger audience than the usual picks.
Leon Bridges -
https://www.leonbridges.com/tour/
His newest album charted at #3 but he'll probably need a big hit single to be considered. He's a young guy with an old school vibe, which could maybe bridge the demographic gap that the SB struggles to appeal to.
Spoon -
http://www.spoontheband.com/#live
Not famous enough, probably, but I've seen them live twice and they're great. Homer pick.