Just as a correction to my above comment - it looks like the December Segwit2x is a little different from the earlier November proposal.
The fork is not the same as the one originally proposed in the NYA but shares some features. The most important part of the Segwit2x fork is the increased block size to 4MB, double what the original proposal called for [2MBs]. It also decreases the block production time from ten minutes to two and a half minutes.
https://bitcoinist.com/back-from-the-dead-segwit2x-fork-announced-for-later-this-week/