Well, so after quite some time of searching I have enough evidence to claim that, yes, there's at least one more Chinese launch before 2020 ends.
Persistent rumors of the Long March 4 series coming back - after reports of the 4B and 4C grounded by unspecified issues back in late October - before the year was out was out for several weeks already, and this was partially proven by the press releases after the Long March 8 flight on Dec. 22. Curiously, while
CALT,
CAST and
XSLC (which also manages WSLC launches) both confirmed that the LM-8 flight is their last of the year, higher up organizations made no such "concluding remarks" - as is another of the major state organizations, SAST. This is in line with previous rumors and points to the last Chinese launch of the year (+) being an SAST rocket flying an SAST payload.
Now for SAST rockets, the LM-2D
has already officially closed out its 2020 schedule after the GF-9-05 launch in August and the LM-6
confirmed after the November Satellogic flight that this was its only of 2020. Which leaves the LM-4 series as the only option.
Previously, before today, the other hint pointing to such a launch was the movement of the Yuan Wang 6 tracking ship, off the western coast of Australia. After tracking the LM-8 flight on December 22 the ship headed
west and, according to those who have AIS tracking data access, is currently stopped at 25°26′ S 89°48′ E, which fits with tracking really down range parts of SSO launches out of Jiuquan.
Then 2 other news essentially confirmed the existence of this launch. Firstly
an official news today on JSLC focusing on cold weather operations (stacking rockets at -15 Celsius, payload air control and launch pad operations etc.) shows that launch operations is going on right now (see photos below).
Paraphasing Rogozin: This is no Boca Chica...The other one is....a NOTAM. Yup, from the Yangon FIR off the Myanmar coast, and fits perfectly with SSO launches out of Jiuquan too!
A0330/20 NOTAMN
Q) VYYF/QWELW/IV/BO/W/000/999/1648N09342E010
A) VYYF B) 2012271538 C) 2012271604
D) 1538-1604
E) OWING TO CHINA SPACE FLIGHT ACTIVITIES.DUE
TO SPACEFLIGHT ACTIVITIES,THE FLIGHT SAFETY
OF THE AIRCRAFT IN FOLLOWING AREAS MAY BE
AFFECTED ON DEC 27,2020 DETAILS ARE AS
FOLLOWS:ON DEC 27,2020,FROM 1538UTC TO
1604 UTC:AREAS:N164832 E0934207-N165801
E0925808-N180928 E0931449-N175952 E0935902,FOUR-
POINT CONNECTION RANGE,VERTICAL ALTITUDE:
SFC-UNL.NO OVF ACTIVITY IS PERMISSIBLE WITHIN
ABV MENTIONED AREA DURING HOURS OF SPACE
FLIGHT ACTIVITIES(CHINA).THE FOLLOWING ATS
ROUTES ARE REROUTED,NOT AVBL IN YANGON FIR.
1)P646-NOT AVBL BTN PTN VOR AND IBITA
(BIDIRECTIONAL)
2)N895/G472-NOT AVBL BTN PTN VOR AND SAGOD
(BIDIRECTIONAL)
F) GND G) UNLSo there you have it, how different hints and puzzles from various sources can help pinpoint the existence and details of a new Chinese spacecraft going to orbit and beyond, when at a glance all we got are "rumors".

(+) CASIC and other "private start-ups" can still pull something out of the blue theoretically, however for CASIC all news on their KZ series RTF went silent after reports in early November that they "are preparing for RTF". Other companies didn't indicate any launch activities within the next few days. Such a launch is very highly unlikely until January at the earliest.