According to the site, they were tipped off that a GTA transition was the rationale behind the rights re-purchase. The article goes on to report that Realtime is claiming ignorance of this rumor. They admit that they pulled back the APB rights from Webzen to "give them some options", and that they'd be open to working with other companies to see the game published. Rockstar hasn't, as yet, commented on the rumor.
Have you been enjoying GTA IV? Would you jump into a GTA MMO?