FORMATS NEEDING COMPETITION (in order): Oldies, Rock, Country, CHR.
Just my opinions........not defending them though. And Yours?
Country doesn't need any more competition...if Kicks and Bull can't make enough competition between them then the format has an issue or the format is glutted (don't forget about all the country rimshots like WNGC, South 107, and Bear, among others).
CHR doesn't need any more competition, either--but the format does need to sort itself out and figure out who is doing what instead of the big perennial AC chase.
Oldies/Classic Top 40 is ripe for the picking. Rock is similar to CHR--fragmented but nobody is sure who is doing what (classic rock, AOR, active rock).