Who decided that segwit2x isn't going to happen? I have read this article: 

https://lists.linuxfoundation.org/pipermail/bitcoin-segwit2x/2017-November/000685.html

Since bitcoin is a decentralized system, who's decided that segwit2x isn't going to be deployed?
Key proponents of the New York Agreement have rescinded their support after large parts of the community opposed their initiative for months. Theoretically, a miner could still activate the fork unilaterally, but the expected value of the Segwit2x network dropped significantly with the exit of said key proponents.