is it possible for someone out there to code a decompiler and recompiler application to remove the 3d effect on 3ds games so that maybe they could be played on a old classic ds
no impossible...3DS console have different hardware..what a pity,there is no flashcart can play 3ds rom.
different hardware isnt a problem, thats what an emulator is for. the problem is that the 3ds is more powerful the DS and you can only emulate systems on hardware thats more powerful than the system being emulated, because the emulation has overheads.
in other words, an inferior system (PC is an exception given how can it be customized, i wouldnt be surprised if some day people can emulate PS3's on their PC's) can never emulate a superior system, the inverse can happen tough
PC is not an exception. Yes people will one day be able to emulate PS3s, but only because PC technology will have advanced sufficiently to become superior to the PS3.