Guild Wars 2

I think it would be possible. It could be implemented with something like changing the amour type and scaling it to that amour type status accordingly and keeping with the rarity and level requirement of the current armor. Now that hero points are a thing they can be refunded based on unlocks without being able to abuse the refund for other resources. This could be bought as an Black Lion consumable. I’m not to sure that which armor skin you switch to matters (maybe just make select a default basic skin and use transmutation stones) and as for the character customization I’m pretty sure that it doesn’t do anything to the story line.
What do you all think? Would there be any other constraints on profession swapping?

Nope, cba to source but this is on par with race change. It wont happen.
Edit to clarify more, your profession is programmed into the personal story, and some parts of the LS as I witnessed on my Engineer, to “undo” what you did would detract from character building which Anet doesn’t really want you to do.
Delete what you want to redo and use tomes to level up, your names when you delete your characters are bound to you for about 24hrs.

Against it – my 13 chars would all become thieves (currently it’s only 5).