I noticed this from the beginning of the new Discourse forums.
There once was a major discussion of an overhaul of the Desktop Viewer, which included the idea that it might be better to change the Make edition to run in read-only mode (and that way the Dynamic Components extensions would run.) Also, that an encrypted read-only (password protected) file format is needed, that only the Pro edition can create, and that the viewer could open.
Ie, that then the Desktop Viewer would be unneeded.
The discussion was basically ended by a staff manager who said that they had some better ideas that would solve these issues, and we should stand by and wait.
Well, what came about (firstly) was the two Mobile Viewer applets, neither of which I use because I do not use mobile devices, and neither of which solved the password-protected FR, but do use there own file format. (No idea if it is encrypted, or protects the intellectual property of the model.)
Secondly, was Trimble Connect. Again not anything I need at the present. Everything I see about it seems cumbersome. (But then I abhor social media sites like Facebook, Google+, LinkedIn, etc. And don't use them.)
Thirdly, we have my.sketchup.com, which is leveraged for the 3DW model webviewer and the two mobile viewer applets. These result from the new overhaul of the main SketchUp graphics pipeline. (Yes, it is good to have common core code driving all these products.)
It is kind of obvious they are not promoting the old Desktop Viewer much anymore.
So, we sort of wasted our time even talking about the overhaul of the Desktop Viewer.
I feel there still is a need for it. Some professionals do not want to try to teach their prospective clients how to use Trimble Connect. They just want to send the client a read-only file, and let them view it in a simple viewer.
What has happened is that 3rd party viewers have filled the gap. This (usually) requires a paid plugin to export a model in some proprietary file format, and the receiving person to install some viewer applet. (LightUp is an example.)
In conclusion, I will not be surprised if the free Desktop Viewer is discontinued in the near future, as it raises no revenue directly.