The PS3 bc was performed via having an entire PS2 chipset onboard as well as a PS1 chip in the original designs. It was 60% of the reason why the PS3 was so expensive at launch and was why it was one of the first things to go in the price drop models. I get that you want emulation, but emulation, as you pointed out doesn't make the company money, if a company invests anything at all into emulation they're doing so out of good will in the first place. Consoles are not PCs this is something we know and have known since their inception. Just because you can do something on a PC, to expect the same on a console is like expecting a typewriter to be compatible with pen ink and being upset when the typewriter's proprietary ribbon prevents you from using a pen to give it ink. From a console specific argument, again I agree that hardware supported BC is the only way you're really going to get solid PS3 support on-console its not worth it. Sony tried pleasing their player base with the PS3 and built in PS2 support day one and what did it get them? A huge hit in market share due to their console costing too much. Its not corporate apology to accept that the business which made the last device I purchased learned that a feature I liked actually lost them sales and therefore took it out. Sony commits to 10 year life-cycles on their hardware, so yes PS4 is coming out but PS3s will still be made and sold for at least another 2 years and there will be continued hardware support for them. Just as the PS2 continued to see titles for years after the PS3 came out. Also, just as the PS2 I'm sure they'll come out with a budget model costing dramatically less so you can have that backup PS3 in case there's content you're jonesing for.
Nick Sony already addressed this and said directly that single player/offline play will be available for all games. Period. They are not locking single player behind a network connection. Also, they integrated much of the Gakai tech throughout the system and at the response times Gakai is able to achieve, running those PSN and classic PS3 titles on a local Sony server and then fed to the PS4 is completely possible even at low broadband speeds and they've yet to comment if any such thing will occur. That said, I wouldn't be surprised if that sort of service was behind a Playstation Plus style paywall as opposed to a per-play/game expense. Why shouldn't it be btw? Its something that costs sony money to operate on an ongoing basis, a single purchase hardly covers the cost.