Are we talking historical or contemporary?
Cause if we talking historically, if you take out the East Coast, you take out EVERYTHING. You can take the West away and Pac is still Pac, minus the hubris of his last years at Deathrow and you don't have Suge perpetuating the virus that is gang culture into Hip Hop.
If we talking contemporary, as in what's going on right now or the past 5 years or so, that's different. Take away the simple formulaic form of music making that the South championed, and maybe the other regions remain competitive lyrically and artistically instead of hopping on trends. OR, maybe people like J. Cole and Kendrick and other high level artists aren't able to emerge because Hip Hop music is never put in a position where it needs a "savior".