With the re-initiation of Flame Legion to the Legions, I think it would not only be really fitting but also super awesome if we gained the ability to roll a Flame Legion Charr.
Not only does it make a lot of sense from a story telling standpoint but from a game play stand point I think its really cool too. They Flame Legion is now our ally, it be really cool to see them running around in the wild as our allies now, just like all of our other allies.
As for the comments about the logistics about this, I think its rather simple:
1. An achievement for completing a certain story step unlocks this customization option in the create a character menu. This option is either grayed out or not visible if you don't have the achievement.
2. This new Flame legion character would start at a raised level(maybe even 80?), and would have a different personal story then a regular character. Meaning he would also have a different starter zone, Grothmar Valley would probably work fine.
3. Some of the other Personal story options would also have to be changed to fit the new story.
4. No tutorial, a short story that introduces some more details about why and how the Flame Legion are re-initiating themselves back into Charr society. Could be as short as 1-2 instances.
5. Different story for Male/female Charr
6. To solve the issue of this character being the commander in future story, make it so Flame Legion Charr cannot open story missions, simple blanket solution.
I know this is pretty extra, but this would be really awesome. One of the biggest things I've felt GW2 is missing is interesting flavor things that don't really effect gameplay. Stuff like the Shadowstone and the hidden quests add a lot of flavor and life to the game.
Though this is 2 or 3 orders of magnitude more work then what the Shadowstone or the Calledbolg epilouge probably took, but its also really cool.