Would Sony do this? No, I don't think so. Looking at PS3 they seem to prefer either a) Remasters (The Last of Us), b)un-released in-house emulation and reselling (PS2 Classics on PS4), or c) PS-Now
Is it technically possible? Since XB1 can emulate the 360 It'd be foolish to say no way. The PS3 has less PPC cores than the 360 and the SPU's can probably be mapped to some compute cores on the GPU. Sony have all the tech specs and docs for the Cell processor and PS3. It's nothing like a group of amateur programs trying to reverse engineer the system.
Do I think Sony should do this? Possibly. I think they could utilise PS-Now better. There should be PS1 and PS2 games on Now by now. They really should have worked out a system where Now can either scan for discs in your Blu-Ray drive or your digital library and allow free-play on the games it finds. But then it's also be nice if UK Now had a bit more parity with US Now - too many games missing from our service!
Would it convince me to upgrade from PS4 to Neo? No, not at all. It's be a nice bonus feature. But I could wait till PS5 for it if that's the future. I'm happy with PS4 and Neo offers nothing for my outlook on gaming over the next couple of years,
Is BC going to be a thing going forward? Yes, I think Sony have tied their colours to the mast and PS4 is now the base machine. PS5, PS5.5, etc, will all play PS4 and Neo games.
What about pre-PS4? Sony are going to exploit their entire back catalogue, right back to PS1. There's already PS2 emulation on PS4. PS1 emulation will be next. PS3 emulation will happen eventually. And you'll have a range of PS1/PS2/PS3 classics you can pay for again and download.
What about Now? It will continue to focus on PS3 for the time being, with PS2 Classics coming direct to PS4. I don't think it will be too long before PS1 and PS2 games hit Now. I also think early PS4 games will start making an appearance on the service before PS5 is released.
Conclusion
- If you want to play old Playstation games legally either a) subscribe to PS-Now, b) Pay for old games that have been emulated (PS2 Classics) via the PSN Store, or c) use eBay to get old machines and games
- If you want to play old games and don't care about legalities - Get a high spec PC and look at ePSXe, PCSX2, and RPCS3