To those who think the next Nexus will be called "Nexus 4 (2013)"
Take a look at this leaked screenshot:
It looks very much like a stylized "5."
And now, take a look at the Nexus 7 wallpaper:
It's a stylized "7."
This is just one of the many reasons that it will be called Nexus 5. I think at this point, it's pretty much confirmed that this will be the name.