Useless then.
Place holder then.
I doubt anybody's going to use these as placeholders. If you can buy the red ones from Nintendo, then you can obviously buy the black ones from Nintendo. Buying red ones to hold you out until you have the ability to replace them with black ones would just be.... Well, stupid.
However, twilightwolf77 could have answered his own question by looking two posts above his own post where Shenske said he would use them for Wonderswan cases. That's probably what I will end up using them on as well, if I can get my hands on them. I might also put my Neo Geo Pocket Color games in there, since the red plastic is pretty much in-keeping with red being a dominant color in the NGPC logo.