Despite the super long development time and lack of any concrete information, and the lead developer leaving the company, Sony has insisted that The Last Guardian is still in development. According to Shuhei Yoshida the game is being re-engineered by a “well-staffed” team at Sony.
There were no specifics about what exactly was being re-engineered, nor what was taking so long and why the development has been surrounded by silence for so long. He does reaffirm that the game has never gone on hiatus and has always been in production.
“So, we’re waiting for the right time to re-introduce The Last Guardian in an appropriate way. I can’t… Well, the game is in development, and it’s well staffed, and [Fumito] Ueda-san is here, working – even though he’s not a Sony employee, he’s dedicated to the product. But we’re not ready to update yet.”
While there is no information the most likely possibility is that The Last Guardian is being re-engineered for the PlayStation 4. In fact, it is conceivable that it was taking so long that Sony decided to move it to their next console as an exclusive to add more prestige to the console and make it even more attractive to consumers.