Neither NCSoft nor PlayStation have made any announcement about a Horizon MMO, much less its cancellation.
::
While the Horizon franchise may ultimately end up not getting an MMO, players can instead check out the single-player offerings, including the recent remaster of the original Horizon Zero Dawn.
::
More recently, the PlayStation has reportedly cancelled development of unnamed titles at Bend Studio and Bluepoint Games.
::
The cancellation might have been a part of the larger trend at PlayStation of shutting down development of live-service titles.