Your biggest issue is making the computers happy with each other. The radio talks to the car's BCM over the databus. For starters, they compare VIN numbers and if they don't match, the radio will refuse to run. It's a anti-theft measure.
While a dealer (and perhaps others) can work around the VIN issue, the question is if you can get computers from different years to talk to each other. I'm guessing you get to be the Ginny pig. And this is all assuming that you're changing a radio for a similar one. If you're switching between base model "green screen", MyLink, and MyLink with Nav, it gets ugly quick. There's a lot of things different.
While a dealer (and perhaps others) can work around the VIN issue, the question is if you can get computers from different years to talk to each other. I'm guessing you get to be the Ginny pig. And this is all assuming that you're changing a radio for a similar one. If you're switching between base model "green screen", MyLink, and MyLink with Nav, it gets ugly quick. There's a lot of things different.