There's been a resurgence recently of city-building/management/strategy games like Cities: Skylines, Planet Coaster, and even They are Billions. Black and White 2 was the perfect god sim game and has had people waiting for another game as good as it for a long time. The opportunity to have a ten-story-tall cow perform miracles and gather followers gave the game the right amount of charm. Updated graphics, more creatures to choose from, and a little more depth in the management tool would go a long way in making this franchise come alive again.
It's worth noting that since Black and White 2 was a product of now-defunct Lionhead Studios, it's unlikely to come back, but we'd love to see what Microsoft could do with the title if they revived the IP.