The only issue I can see with doing that is the DLL may be locked by the computer that opens it, thus limiting the ability of you to overwrite it.
A simple fix would be a script added to the startup of each workstation to copy the file locally if a new version is available.
I have actually written some of my programs to check for updates and download the new file if there is an update, but it can be a trick to do ...
If you want to do that, simply have the program when it starts, check a network location (make sure error checking is in place so it doesn't crash if the network is not available) for a file that holds the current version, then if the version in the file is different, copy the file locally as a different file name (temp folder), start the second copy of the program from the temp folder, end the first copy, the second copy checks to see if it is running from the temp folder, if it is, copy itself to the location where the first program was located overwriting the first program.
Yes .. convoluted .. but it works .. and there is lots of coding to make it work properly ... in the end it will be worth it though ..