Taking a page from Square Enix, I expect Playstation 3 - II

But seriously, seeing how the Playstation Network was changed to the Sony Entertainment Network, I wouldn't be surprised if the Playstation name was dropped altogether. Maybe like the Sony Gamestation or something along those lines - Sony would definitely be in the name.

Playstation Stay-The-Fuck-Still?

Nah, just kidding. I expect them to simply name it Playstation 4. No reason to drop the name in my opinion.

PS4, great things come in fours.

And 4 can be pronounced shi or yon.

It has to be ps3, I'm sure Sony as had.. well 12 years when they named ps2 or 5 years when they named ps3

PS 4 U ;)

Maybe with PS4 it will be a bit soon, but if Sony keeps coming last against its competitors it won't matter how strong the name used to be, it's a time for a rebranding. I also think you underestimate the average console buyer, and the brandname "Sony".

I like Rol's Quattro

Quattro is associated with semi-luxury cars, as well as a big name in the Gundam Universe and is referenced in many anime.

The name of Italy's 15th century artistic movement.

It also sounds slick, and that makes Sony hard. I'd say PSQuattro

Common people don't know total lifetime sales (although obviously a huge user base will help keeping a brand name strong even if there is a current sales flection), they know better how popular is a product in the present time, and currently PS3 is the best seller home console and second after 3DS considering portables too, so the PlayStation brand is again one of the strongest in the gaming market. And Sony invested huge resources and bled money for more than three years and a half (they stopped losing money on HW in May-June 2010) to achieve it, it wouldn't make sense to throw it away now.