The more you add to this idea, the less I find it relevant to what consumers will need to make mp3 a dominant format over CDs.
The way I see it, you need three things.
The compact size of a CD
The affordability of a CD/player combo
The quality of CD play back
Mp3s already improve on the first, they're approaching it in the second, and they match the third. You have a situation where mp3 format is as easy and available and close to as affordable as CDs. I don't think the player accessibilty has anything to do with how mp3s will come to dominate a music market.
That IR technology already exists for CD players, there is no technical complication applying it to an mp3 player, but even ignoring the problem with line of site when you're jogging for the connection, I don't think that would have anything to do with mp3s needing it to replace CDs, which was, after all the original point you made: that mp3s need media and/or a player that matches CD playback.