And considering it's worked out pretty well for them, I'm surprised Sony isn't taking it more seriously.
Two reasons : Ken's original vision was that the PS3 wouldn't need another gen iteration. Not getting into how or why since it's all just hypothetical now.
Now, Sony doesn't see the PS as their way forward. Also, nobody there actually understands how the thing works anymore.
If I were Sony, I'd have some sort of conversion kit that can upgrade your PS3 to a PS4 for a fraction of the price of a new console when Microsoft pulls out their new one
Not too far off of Ken's vision methinks. But I wouldn't be surprised if the PS3 was Sonys last foray into the console market for some time (I wouldn't be surprised if it wasn't tho, either).