The PS4 might not restrict the sale of used games, but that probably doesn't mean that the publishers can't do that on their own, if they really wanted.
They definitely could, especially in a dedicated online game. However since, as far as I can tell, the console as a WHOLE isn't forced to be always online, they have fewer channels for being derpy.
Also thanks to Microsoft and EA's /stuff/ as of late there's probably going to be a marked stigma about going rampant with DRM on a system that's not really enforcing it.
It was so in and awesome to take a shit on Sony. Sony was the laughing stock of the gaming world!
Seems like Sony got their act together, whereas Microsoft is... starting to do the same kind of stuff that was making Sony have all those security issues in the first place.
24/7 internet connection + mandatory always-on webcam thingy + the kind of draconian DRM policies that just get hackers' jimmies a-rustlin' = you're going to get hacked and they're going to be some pretty malicious hacks.