I really hope they will offer a slightly more expensive version with BC. Can't be that expensive to pack the PS3's CPU (would it even need the GPU, too?) in as well by 2013/2014.
Disc games could be emulated on PC at some point, but DD games are locked&lost in your PSN account and would be lost with the hardware.
I don't buy used games nor do I usually sell them, so this anti-used games thing would actually give me MORE for my money as I would basically get the DD version for free as well (and hopefully those would work on future Playstations via BC...).
Get the best of both worlds, some awesome CE/packing and play the game w/o the disc (though no forced full-installs would be preferred).
Most of the time I wait for some nice retail sales (UK online shops say hello), so I often pay far less than many of the used-buyers @gamestop etc. anyway.
However, they need to have the same sharing system like on the PS3.
That means lock it to your PSN account -> sign in with your account on friend's console -> can play the full game. Also, every other account on a PS4 should be able to play the game as well (on 3+ different PS4s at the same time).
That way this won't affect borrowing games from friends, showing games to friends etc.