What's changing in the train schedule between Ulan Bator and China ? Everyone's confused.

Something is changing in the service from Ulan Bator to Datong (and Hohhot) from about July 8 this year. A summary of what's really happening would be appreciated (is this a speed improvement ? new routing ? can you summarise the new through services from UB to China and vice versa after July 8 please ?). Advice I am getting is that it will no longer be possible to travel directly between Ulan Bator and Jining or Datong, for example, after about July 8.