Besides crew and pilots, no one in the game has appeared across multiple ships or as different versions of themselves. Many other minis games do this and it would be easy to apply to Xwing.
I'll start with Vader since he seems to cover a lot of ground.
Old: Darth Vader: As is tie Advanced Pilot, represents the "basic" Vader.
New: Darth Vader, Sith Lord: Still flying the advanced, new pilot ability (Maybe something force related) could "recost" him to be more in line with newer models.
Benefit: we get a "new" pilot, we get another pilot for an unused ship, we get a point fix for a ship that needs it. Vader is a bigger bad Azz than currently depicted in the game.
Bonus: if we ever get clone wars we could get, Darth Vader, sith apprentice and even Anakin Skywalker.
Ok.
What other pilots could ship hop, deserve a better ship, deserve a different ship, or deserve a powered up/down version of themself? Mr. Steele is one people also clamor for (shocking that he also happens to be seated in a tie advanced).
Luke Skywalker, rookie starfighter (AKA lucky newb): PS3, You may reroll 1 dice from any torpedo attack
Boba Fet, Bounty Hunter: Before you reveal your first manuver, gain a TL on any one enemy craft. While you have a TL you may reroll 1 att vs that ship or one evade vs. that ships attacks.
Tycho, Academy Pilot: Tie Fighter!
Tycho the defector: Xwing!
Tycho flew a lot of ships. Before Aces I would say he needed a boost, I think he'll be ok now but he also provides a lot of easy port overs.