an analogy to try and help.
for millions and millions of years the colorado river has carved the wonders of the grand canyon. this eon was a little rainy and canyon development was significant, that eon was a little dry and the river's impact on the canyon is less. the river always runs, it is always working its wonders on the canyon.
bama football is like the grand canyon. the most awe inspiring and beautiful feature within the landscape of college football. some years in the bottom of the canyon where the battle takes place you have a Paul Bryant or a saban. in these years the canyon's features are embelished. some years you have mike dubose, some years ncaa sanctions and you can barely see an impact. when saban leaves alabama(and he will leave alabama) there could be a little flow redirected to wash some brackish water out the bayou for a year or two. who knows?
saban has been huge. saban may continue to be huge at bama. but saban aint bigger than bama. he may leave, but the natural order of things is always eventually restored and the tide will just keep on rolling, with nick, without nick.
p.s. i bet when saban is at texas and bama kicks his butt in the "football tournament" he wont cry because he lost whoever his "colt mccoy" is that year!