Surely once the kid gets a PS3, he doesn't play any more PS2 games? That's the major point here - who actually uses BC? At this point in the cycle has it any place to play in all any but the most niche of users? I'm playing Rogue Galaxy and then AFAICS that's it for my PS2 despite not having a PS3 nor expecting to get one any time soon. There's nothing coming out for it that interests me. How much less appeal does PS2 have when you do have a PS3? What does it offer that PS3 can't? I guess if you still have FFXII to play or something, it might see use.
I still have several uncompleted PS2 games and a lot of guitar hero / singstar type of stuff that is very demanded on house party type of situations. BC is an issue of having one ugly box and several cables less to clutter my living room with.
Given the choice, I'd gladly pay like 50€ extra to have BC just to be able to fit all my electronics under my TV (which should easily cover EE and other BC chips).