Xiaomi Mi MIX 4 will not be shown on December 10th. They will only tell about the date of the announcement. The presentation will take place at the end of December.
Characteristics:
Curved display
QuadHD Resolution
60, 90 and 120HZ
Snapdragon 855+
UFS 3.0
Under display front camera:
12MP + 2MP
Quad camera:
108MP + 20MP + 12MP + 5MP
and STEREO!
Also, Xiaomi will strongly deny the imminent release of the new MIX in order to surprise at the end of the year.