Unreal Engine's 4.14 update has been released and in the patch notes there are some details that would suggest changes to PSN's approach to account names.
As spotted on NeoGAF by user Kirbasin, the update mentions PS4 SDK version 4.008.061, saying that Sony has updated developed recommendations to allow users to be identified by account ID rather that online ID. The update also references switching from the previous method of returning online ID to one that uses account ID.
This doesn't confirm anything but does hint that Sony is implementing a change that PSN users have been requesting for a while now, which is a name change system, involving unbinding account and online IDs together, allowing you to change account IDs for free. Would this be a feature you'd like?