I think it is a given that PS4 games will be BC. and will be at 4K. All the games people bought and will buy this gen. Even though they may not use to too often in 3yrs time but definitely want to have it in their library after upgrading to PS5. I am not sure most people would simply dump all that stuff and happily upgrade to PS5. Ideally they would want to have access to all PS games but I think that is unlikely to happen.

It is something I've been thinking about. If the PS5 is going to share the same architecture as the PS4, there is no reason why there shouldn't be backwards compatibility.

There better be backwards compatibility, the PS2 and PS3 had it, the PS4 itself was an anomaly.

It also makes sense because both Nintendo and Microsoft are in good position to provide BC. I guess Sony doesn't want to be kept behind them. With NSW, Nintendo might be able to handle the device like Apple handles iPad. Microsoft is already providing BC the best as they can.

I guess we're approaching an industry 100% committed to BC.