> Will they be willing to die, given that operating a large pool must be quite lucrative?
I'm not an expert, but I think that they wouldn't have a choice, since they would be outnumbered, and no one would recognize the legitimacy of their new bitcoins. Having 51% of the hashing power doesn't give them 51% of the vote when it comes to this community decision.
Outnumbered by who? The people securing the network right now are overwhelmingly doing it on pools. If the blockchain forks, the network not supported by pools may literally be unable to continue thanks to the extremely high difficulty it will have post-fork (as has happened with other, smaller coins, thanks to coin-hopping pools).
If most of the Bitcoin Core clients, including all the "light" wallet servers like Electrum and Mycelium, and businesses (like Coinbase) switched over, then the bitcoins created by the miners on the "old" blockchain will completely lose their value as they would not have any uses. They'd have no choice but to switch.
I am pretty sure there is nowhere in the world where 1/x of the people really get a 1/x say in anything.
Things like votes are attempts to make it so, but as a practical matter if you only get to vote between a few choices created by blocks of power in which you are not an elite (i.e political parties), your vote cannot possibly reflect what you want in any meaningful way.
Tragically, people are so used to voting between choices other people set out for them that they delude themselves into thinking that they are being fairly represented, and that their beliefs really should line up in one of a few belief-bundles determined by team names.
I'm not an expert, but I think that they wouldn't have a choice, since they would be outnumbered, and no one would recognize the legitimacy of their new bitcoins. Having 51% of the hashing power doesn't give them 51% of the vote when it comes to this community decision.