My guess so far is a cooperation with Fuji, a mirrorless camera with a 44x33mm sensor, with exchangable lenses. New lens mount, but H lenses can be attached (with autofocus) via adapter. Attractively priced (for being MF), targeted at consumers.
However I guess on-chip auto-focus will require a different chip than the current Sony 44x33... so maybe it's something else.
The "game changer" term is almost always an exaggeration from marketing, but if it's shown to be the first mirrorless MF system and on top of that attractively priced, it's as close as it can be to a game changer.
Sure Pentax 645z is attractively priced and all, but it's a bulky monster crippled by it's huge flange distance. A similar priced mirrorless body with the same sensor size it could be a hit.