I expect the participants who have signed the NYA to follow through and support the S2X-token, at least for a while - but at the end of the day, money talks - both exchanges and miners ultimately have to do whatever gives the best profit.

With 15% hash power and a 1 MB block size limit, transactions will hardly go through at the legacy chain. I fail to understand how a bitcoin with almost no utility value, a bitcoin that cannot be withdrawn nor deposited to the exchanges, can have any value. Possibly BitFury and BTCC will defect the NYA - but still I believe the hash power will be too low to make the legacy chain usable.

Then again, I have been wrong before and I will probably be wrong again. Two thoughts:

• One thing we saw with the 1st of August fork (even if it was very clear that there was good replay barriers and no risk of transacting during the period), quite many exchanges and businesses shut down the possibility to withdraw or deposit while the fork took place, some even for days, and I guess quite many individuals also had been advised not to transact right before or after the fork. There was actually quite some free capacity in the blocks. If the transaction volume will decrease to 20% of normal, then 20% hashing power is enough to clear the backlog. The confirmations will be slow, though.
• Perhaps the inability for people to deposit into the exchanges, as well as the low inflation will cause the legacy bitcoin price to grow (as it will be difficult to buy it from the exchanges). If the relative pricing of the new tokens will be anywhere in the ballpark of the current Bitfinex futures, then miners will most likely defect the NYA and mine on the legacy chain, and the S2X-chain will die.

The Terms and Conditions on Bitfinex is not that good, particularly that the T&C can be changed by Bitfinex anytime. By saying that they will use the designation "BTC" on the 1MB-chain after the fork they are clearly showing where their loyality is. Also, any "technical failure" is sufficient to deem the BT2-tokens as worthless. Despite all this, I've been buying up some BT2-futures as I see BT2-domination as the most likely outcome, though it feels a bit risky buying it from Bitfinex. I wish other exchanges would follow up and offer similar bets.