If we look at the progress in the 3DS emulator scene we notice one very rough and unfinished nes. One snes emulation that has gone rather far but has a LOT of work left before it is fully playable. We have one gb/gbc and two slow gba emulators. PS1 emulation can sure be done on the 3ds. But it will NOT happen unless something extremely drastic happens. Like there would be hundreds of competent new developers in the 3ds scene Over a night. Not going to happen.
You'll never have enough cpu power to run a PS1, even for 2D games, and that's why you might never see anyone trying as coders are fully aware of the specs they barely require to emulate something and won't try something which don't seem to be feasible (not to mention they don't seem to exist a lot of coders interested to make some emulators on 3DS, if you look at it, most people who worked on DS never worked on 3DS yet, like thoses who did NesDS, Goomba, SnesDS, JenesisDS, etc...).