Anyone?
I expect that they will handle it similar to the BCC/BCH fork. Therefore I would suggest that you move
your funds out of Bitfinex early enough and take control of your own private keys.
By doing this, you ensure that you will get 100% of all upcoming fork coins and don´t have to worry about
exchanges using obscure calculations to decide how many S2X coins you get awarded.
This should be a no-brainer for you as you already made a bad experience with Bitfinex with the previous fork.