SegWit2x is being deployed in its testnet to all working group members on July 14, and the period for live adoption starts on July 21, with an August 1 deadline for necessary support to avoid issues.
SegWit2x is competing with another proposal: BIP 148.
Developers have worked to make these two compatible, so, if enough mining pools support SegWit2x before August 1, bitcoin should avoid a split.
More details here:
http://www.coindesk.com/explainer-what-is-segwit2x-and-what-does-it-mean-for-bitcoin/
