I saw the thread and saw the photo also.
You wont have to get the whole camera module replaced.
That cover is just a circular piece of plastic over the back panel (the inner shell) , the one u see when you remove the removable back panel.
Camera module is this

Of-couse it can be removed but in your case no need
And this is the plastic Cover for the camera
Which is removable for most phones with some expertise.
Worst case if that is non removable
you can still have the shell replaced which looks like this
PS. Images for illustrational purpose only (this is my old lagdroid) .. its not a lumia .. i will never open my lumia :P :P
Cheers mate . spares will be available.