LittleBigPlanet 3 is reportedly in development at UK studio Sumo Digital, and apparently has been for more than a year.
VG247 claims multiple sources have stated via email that the developer is working on the third major (and sixth total) release in Sony and Media Molecule's franchise – with the two approaching the studio well over a year” about it.
Sumo Digital has previous ties to the LBP series, developing LittleBigPlanet 2′s cross controller patch with the PS Vita last year. A source also added that Media Molecule has outsourced ongoing development of the current releases to the studio.
A Sony rep has since responded to the report, stating that the company [doesn't] comment on rumour and speculation.”