Syria

Syrian radio seems like off air since weeks on 783 kHz. I hear only the spanish, and a persian station underneath it. No trace of the Syrian signal. Usually it dominates the frequency over the Spanish in Hungary.
László Tringer (2021-01-03)

Netherlands

Translated from Google:
“A number of medium wave transmitters stop its broadcasts via medium wave. There are also a number of new stations started broadcasting via the ‘AM’.

As of January 1, Nostalgie AM from Siddeburen in Groningen will stop its broadcasts via the medium wave frequency 1395 kHz. The owner of the radio station says that after 1.5 years of broadcasts via medium wave, it is time for something else.

Radio Emmeloord has this afternoon, Wednesday December 30, stopped its broadcasts via medium wave on
1224 kHz. The radio station has also been broadcasting via DAB + in the Emmeloord region for a number of months and therefore, according to the radio station, it no longer makes sense to broadcast via medium wave. In addition, the radio station can be listened to worldwide via the Internet. Incidentally, it is not the first time that the radio station has discontinued its medium wave broadcasts.
It also looked gloomy for the broadcasts of Extra AM from Amsterdam on 1332 kHz. Due to the loss of a number of sponsors, it was not certain whether the broadcasts could continue after January 1.
A crowdfunding campaign has since raised enough money to allow the broadcasts to continue for the time being.

Not only are radio stations disappearing from the medium wave, but new radio stations are also being added. For example, Antenne Domstad and Radio Monique recently started broadcasting via medium wave.
Mediamagazine.nl 30th December 2020
Tom Kamp to A-DX Fernempfang fb group (2021-01-01)

Netherlands

This afternoon Radio Emmeloord switches off their LPAM station on 1224 kHz with the reason that they have enough DAB and online listeners so that AM is no longer a useful addition.
https://radio-tv-nederland.nl (2020-12-30)
Hopefully this is the only station that will switch off this year.
Also Groeistad 675 kHz seems to be off-the-air again.
Marco (2020-12-31)

Canada

Regarding CJMS 1040 AM in Saint-Constant, Quebec, I just received confirmation from Normand Martel who spoke with someone at the station. They are now “officially” shut down based on a decision from the CRTC to revoke their license. They had been continuing to broadcast awaiting the results of an appeal on the decision. According to a spokesperson from the station, they are now gone for good. The station was noted off the air late this week.
Sheldon Harvey, Canadian Int. DX Club, CKUT’s International Radio Report to WOR groups.io (2020-12-26)

Australia

Some recent observations:
1. Former Rete Italia transmitter in Launceston, Tasmania on 1611kHz which has been carrying SBS Pop Desi for a long while appears to have now been switched off. Not sure when this happened. Was on some recent months ago.
2. Former Rete Italia transmitter in Gladstone, Qld on 1620kHz is, after over 3 years still transmitting an o/c.
Ian (AUS) to mwmasts groups.io (2020-12-20)

United States

Radio Disney Comes to an End.
Disney has announced that Radio Disney and Radio Disney Country will be coming to an end in early 2021.
Radio Disney started out in 1996 as a network of radio stations. Then it moved primarily to FM HD2 stations, and finally in 2015 they became Internet radio stations.
But in Los Angeles (Pasadena), it remained a radio station on 1110 AM, first as Radio Disney KDIS (2003 — 2017), and then as Radio Disney Country KRDC (2017 — present).
Variety.com
Steve Mittman to MWDX – The National Radio Club fb group (2020-12-04)

New Zealand

NZ Medium Wave Changes
New Plymouth stations RNZ National 918, NewsTalk ZB 1053 and Coast 1359 all left the air on 13 November, opening up new DX opportunities for Kiwi DXers.
The sole remaining New Plymouth AM station – Gold AM on 774 will remain, though a relocation of the transmitter is anticipated.
The other NZ station on 1359 – More FM Queenstown – has also ceased broadcasting.
Bryan Clark to DXing.info fb group (2020-11-13)

United Kingdom

Two more MW closures today.
1015 UTC Lewsey Farm 828kHz (Smooth Radio Herts Beds Bucks South) 
1207 UTC Kempston 792kHz (Smooth Radio Herts Beds Bucks North) 
These transmitters started in 1971 as Chiltern Radio South and Chiltern Radio Ouse Valley respectively. 
Later Super Gold hosted from the South studio in Dunstable then Gold then Smooth Radio. 
Permanent closure from today. 
James Robinson (2020-11-02)