In the past, cameras are built with a lens that focus light onto a film and a separate viewfinder for framing the scene. This has a disadvantage as the scene as appeared to the viewfinder and through the lens may be considerably different due to parallax.
The innovation of SLR (single lens reflex) cameras has changed this radically, in the way that the viewfinder is able to view the scene through the same lens that the image will be taken. Due to this, another advantage is that you are able to change the lens and still able to compose the scene without much difficulty. You are not able to do that in a fixed-lens camera.
However, as we enter the digital age, the scene has changed yet again. Now, with ccd/ cmos imaging, live view is possible even on point and shoot cameras, which make viewfinders increasingly redundant especially in smaller PNS cameras. In fact, most camera still holds a viewfinder mostly for decorative purposes, they are almost never used for phototaking.
That said, the later models of DSLR now possess the technology of live viewing as well. Now, with live viewing technology, is this going to make the viewfinders on DSLR redundant in the near future, since we will still be able to frame the scene on the LCD screen? Is the SLR mechanism going to be useless? Is there still a point in keeping the SLR technology, since from now on, a camera can use changeable lenses even without a mirror reflex to redirect the view to the viewfinder?