I am torn between PS4.5 and PS4K.. but will probably be PS4K
PS4K sounds like a perfect name.
What I THINK it will be called? I'll predict it's a full on fail and called the New PS4.
PS4K or possibly PSX.
I'm with everyone else, I think "PS4" is simple, straight to the point, and kinda catchy even.
"PS4K" has the nicest ring to it, and really pushes the idea of a 4K system. (Though I'd prefer "PS41080p60fps" myself!)