Chewbacca being a Wookiee (who live for centuries) means he ages at a different rate to Han. One of those interesting character questions unique to SF&F.

In the OT we were catching Han and Chewie at the moment when they were both the same age (So to speak). Equals, brothers in arms. In TFA Han is much older than Chewie and we see Chewie making sure Han wraps up warm against the cold, like a caring son. So in a young Han Solo movie will Han relate to Chewie as something of a big-brother, or even a father figure?