The developpment of DS emulators already started, and so far they can play some homebrew demos (simple effects mostly)/games (tetris) (which, considering that the DS was released only 3 months ago in the US isn't that bad). I'm pretty sure that in time, DS roms will be just as easy to get as gba roms, in fact, there is already one rom dump made.

Oh, also, playstation emulation works pretty damn well, the playstation 2 emulation is another matter. And both the psx ad dc isos, back when the consoles weren't completely outdone, were piss easy to find.