No, I mean the space to slot a blue-ray driver in if you want to. Maybe I did not make that clear enough. In something like the Mac G4 Towers of old you could slot things into 5 1/4 bays such as Zip discs, blue ray players, audio ports of whatever you wanted really.

As I pointed out the problem with current thunderbold setup is that they seldom give enough power to drive the devices you connect. I have a Blue Ray player which I can connect with thunderbolt but it requires external power. Same with my external LaCie disk.

I just don't want to have half a dozen black power adapter and a jungle of wires on my desk. Having bays where you can fit devices allows you to add extensions without all the clutter.