Demographic change is happening much, much faster in Arizona than in Georgia. While black turnout is not unlikely to be somewhat depressed in Georgia post-Obama, the Hispanic turnout will eventually increase across the nation as latinos age (older voters turn out at much higher rates). In no other state the Hispanic population is increasing faster than in Arizona, not even in Texas or Nevada. (At least that was the situation in the last decade, although their new, stricter policies might have changed the situation somewhat.) Another thing that will drive Hispanic turnout in 2016 and beyond is candidates more suited to appeal to this demographic, either by being latinos themselves (Rubio, Martinez, Castro, Cruz, Menendez, Solis), by having a multiracial family (Jeb Bush) or just by having a strong appeal towards latinos (Hillary). Also Arizona is socially liberal/libertarian and less religious than the average state.
By 2016, Arizona will be more likely than Georgia to vote Democratic because of the surging Hispanic citizen population. By 2020 and 2024, Arizona will be much more likely. By 2024, only a very weak Democratic candidate will be able to lose the popular vote in Arizona I think. Arizona will be the new Nevada eventually. Arizona will be one of the most important battleground states in 2016 and 2020 I'm sure. Georgia's direction will be slower and much more uncertain. Hillary will probably/possibly make Georgia a battleground in 2016, but only if she can win convincingly/in a landslide. She also has the strenght of being a regional/"Southern" candidate in many people's eyes, although she's originally from Illinois and having represented New York in Congress.
This much I can agree with but for the states to change parties, trends would have to continue and the Republican's inability to reach out to minorities would have to continue. I don't think Hillary Clinton will be hurt in the south from representing a northern state with the exception of Arkansas which she abandoned as too good for. There could be a backlash there, but she'll still get at least 34%. Arkansas isn't the point here. Bottom line is that Obama didn't win either Georgia or Arizona in 2008 and I don't see Clinton winning by quite the same national margin. Even without McCain, I think Obama would've come up a few points short in Arizona. Light redness is nothing new to the state either.