...if motorstorm had continued, FH5 is what it would have become no doubt.
I still remember a few moments of assuming, when it was first announced, that DriveClub would be an open-world racing game. It seemed like, Oh cool Sony have their own FH / TDU, that'll be a good alternative to Gran Turismo since GT will never have a straight driving world mode... and then, it became clear that it was another circuit racer, confusingly another game in GT territory. Was not surprised by its short lifespan, sadly.
Open-world seemed to be a possible direction for a next-gen MotorStorm, although the courses were pretty carefully groomed for the various vehicle classes so I'm not sure how that would have worked out. (Evolution never had an engine for it anyway, despite some really impressive vistas in WRC & Motorstorm, but it's still something I wish had happened somehow.)