We finally have some reliable Sony rumors to report - Sony registered a new fixed camera under the code name WW151602:
WW151602
The WW151602 is most likely a replacement for the current RX0 model (because of the Sony NP-BJ1 battery listed in the registration).
Nokishita also reports that Sony will announce at least one more mirrorless camera in the first half of 2019.
I updated the list of upcoming cameras/lenses.