Sony should at least include a ps3 emulator. I dont like the idea of having to turn one console off and turn another on to play a older game. Sony has the ability to develop an emulator for the ps3. If you bought 10 ps3 games that were 40 dollars each, thats 400 dollars. I mean it would be nice to play Fallout 3, GTA IV, Gran Turismo or Just Cause 2 on the ps4!
The thing with emulators is that, well they're just that an emulator. And while a PS3 isn't that powerful compared to hardware today. if if you take the raw FLOPS or whatever of the PS3, the PS4 would in most cases be able to emulate that just fine. The issue is that the PS3 isn't just another architecture, had it just been another PowerPC architecture sure, but with the special split architecture, then the power required to emulate it rises exponentially. Effectively it would need a Cell CPU in the PS4 to do it, like the PS3 had the emotion engine in the start.
in any cases they'll use their streaming technology to give you BC when you have internet, and since the PS3 games are all 720 or below the compression quality reduction won't be terrible.