Questions on the end of support for FlashPlayer

Here is the official end-of-life announcement.  It links to each of the roadmaps published by the major US browser developers.  In addition to our changes to Flash Player, each browser developer is removing support for browser plug-ins, and planning to add various in-product messages about Flash going away.  Their timelines are independent.  These may be important additional considerations, depending on your organization and the browsers you use.   

https://theblog.adobe.com/adobe-flash-update/

Flash Player releases monthly, in coordination with Microsoft Patch Tuesday.  The dates that we documented were "The latter half of 2020", which is basically now.  We won't have exact version numbers for a given monthly release until we're done testing, and since we release monthly, there's a very narrow window between when testing is complete and when it ships.  We follow a reasonably predictable pattern.  You can see the update history in the release notes: https://helpx.adobe.com/flash-player/flash-player-releasenotes.html 

If you wish to suppress the prompts for your organization, the necessary mms.cfg flags are documented in the administrator's guide (in the English version, we've added the relevant information to the beginning of Chapter 5, Enterprise Enablement).

I believe that you are conflating a couple different things: 

The Enteprise Enablement Allow List / Whitelist feature allows an organization to restrict Flash Player's behavior to only load content from domains that you approve.  This feature reduces your potential attack surface (i.e. things like Flash-based ads and games would no longer load on your enteprise machines).  In a situation where you absolutely must run a version of Flash Player beyond the period of time when it will receive security updates, we're effectively forcing the administrator to restrict it to only your trusted, critical content. That feature works now, so you can limit Flash Player's attack surface at any time between now and the end of the year, at which point must have a defined policy if you want Flash to load anything.  We've also provided convenience features like AllowListPreview to help you identify the content that must be allowed on your network and only allow what is absolutely necessary.

The Uninstall Prompt is a separate issue, and it can be suppressed by setting EOLUninstallDisable=1 in mms.cfg.  You can also specify that now in your mms.cfg, and at the point that the notification goes live, it should be suppressed for your managed machines.

We also provide the ability for enterprise administrators to control when their clients get automatic updates by allowing you to disable automatic updates from Adobe.  You can then provide them to users after you test, through common software management solutions, or by hosting your own Flash Player update server.  See "Background Updates from an internal server" (and the Player Installation chapter in general) for more information on your options.

Again, your users will probably also see some prompts from the browser vendors in various infobars and notifications (these would be documented in the browser partners' blog posts), and any options relevant to suppressing those notifications would had to be dealt through the administrative controls for each individual browser.

Hope that helps!

You should know that Flash Player will be blocked in all the major browsers at the end of the year. You cannot use a whitelist in Flash Player to keep them working.