SonyAlphaRumors indicates a source is feeding it details about a new crop camera to be launched next month by Sony. The camera would be a direct replacement of the A6600 and comprise a modest revision in most respects.
The one area for which site expects a major upgrade is the sensor, which may significantly increase in resolution.
The A6600 is notable in that, while other companies have matched or nearly-matched its critical autofocus capabilities in the past year and a half, only Sony has pushed that same technology down into its APS-C sensor cameras.