Well, Sony just killed it.
Sony's Jack Tretton jas just confirmed that the PS4 will feature no used game regulation whatsoever, using the same pre-owned model we currently enjoy. "We believe in the model that people invest in today," he stated, somewhat smugly. "When people buy a PS4 disc, they can trade it in, lend it to a friend or keep it forever."
He also took somewhat obvious joy in confirming that there's no online check-in requirement, and games can be played offline without restriction or penalty.
However, it appears that PlayStation Plus subscription might be required for online play. We're looking into it.