Nothing if configured correctly for that scenario.
I *think* if you copy dosbox.conf into that folder or create a new dosbox.conf in that folder then the rights would be inherited and the user would only have read-only access to that file. Only way around that would be to run DOSBox as administrator or modify the rights to grant write permission to dosbox.conf.
But let's say:
1. User installs DOSBox 0.73.
2. User wants to ignore warnings and copy or create dosbox.conf to the DOSBox directory.
3. Assuming user is doing like they are supposed to and running DOSBox as a standard user then whever they want to change a setting in dosbox.conf they will not be able to and they will spam the forum wondering wtf stupid DOSBox won't let them change their settings so then they will do ignorant things like the following to get DOSBox to work (either one of the below or a combination):
Run DOSBox in compatibility mode (don't ask).
Change permissions on C:\ or Program files to grant write access. (Hey it fixed their problem right?)
Add themselves to Local Admins (Because it makes things so much easier)
Turn off UAC (Because it makes things so much easier)
Create a new folder in C:\ or C:\Program Files and then copy the contents of the DOSBox directory into it (So they can write to the DOSbox directory.
Yes I have seen all of the above and more in reference to DOSBox.