It's well known that CLT was a money-maker for Doug and Scott, and will likely continue to be into the future. There's no other reasonable location to put a southeast hub. MIA is primarily Latin America and other international destinations. PHL is fine for the Northeast and international, but can't reasonably serve all the smaller markets in the southeast. If they shutter CLT, they'll basically hand over the SE United States to Delta and Southwest.
PHX is a different matter...it's really too hot to serve as a good jumping off point for the far east Asian markets. It could possibly serve as a decent west-coast domestic hub, but that depends on how much LAX can grow. If LAX stays relatively flat, they'll probably make LAX more of an international gateway while keeping more of the domestic stuff out of PHX.
I have heard good rumors that the PHX training center will most likely close regardless of the future of the PHX domicile.