I agree the days of SLR may be limited.
See the predictions I made in 2004:
There are already prototypes of non-SLR cameras with interchangeable lenses. I think Olympus announced them a few months ago. And if you want to talk about frames per second, Casio announced a 60 fps camera just a few days ago.
Who says you need an optical viewfinder to compose pictures? In fact, who says you need the LCD to compose pictures? Would really be nice to have a camera you can shoot from the hip, but with a wireless bluetooth viewfinder on a head-mounted or spectacle-mounted display. My old Nikon Coolpix 990 introduced me to the concept of composing and shooting from the hip. Really innovative.