Considering Sony said before the launch of PS3 "BC will continue on forever'... I would consider it par for the course. Sony should have kept their word to begin with. That is one of the things that SOLD the PS2. Sony is the company that made BC popular in modern console gaming.
I think PS4 should have native PS1,PS2 and PS3 BC. Next gen, their console should have native, disc based PS1, PS2,PS3 and PS4 gaming. Just like they promised.