In their prior blog post they indicated that at the time of the fork, the existing chain will be called Bitcoin and the Segwit2x fork will be called Bitcoin2x.
However, some customers asked them to clarify what will happen after the fork. They are going to call the chain with the most accumulated difficulty Bitcoin.
They will make a determination on this change, once they believe the forks are in a stable state. They may consider other factors such as market cap or community support to determine stability.
It’s important for them to keep a neutral position in any fork. They believe that letting the market decide is the best way to ensure that Bitcoin remains a fair and open platform.
Get 10$ worth bitcoin for free - https://www.coinbase.com/join/58188a20b93eb567d1b760d3