If XT is adopted, XT wins, there's no other chain, or at least there's no other chain with value.
You may find someone that lived in a cave for the past year and scam them using the abandoned chain, but that's not something you'll want to brag about, I think...
Honestly. I dont mean to turn this into a debate. But why wouldn't XT win? I read our volumes are only 30-40% of block size now.. but there is a real risk of hitting a limit if bitcoin continues to be adopted, which it will. I see no reason why XT wouldn't win. Though I am certainly disappointed at the dev's of both sides. Bitcoin has always been an amazing concept with the overshadow of greed and shady business. I wish it were not so.