Too big to fail? Sony has plenty of very successful exclusive games. The last GT universally praised was GT4, 14 years ago!
GT used to be a juggernaut and things have changed. Even if GT is more than a game to me, we shouldn't be blinded by nostalgia. Just look at Forza Horizon, arcade or sim whatever it's a car game aiming to the mass market (unlike Assetto Corsa).
No weather conditions, statick TOD, only two tracks at night, laughable AI, no true career mode with a sense of achievement, many missing features :
-360° camera view;
-camera view options like a G sensitive camera, it's stiff and looks boring;
-the best 3D models but no actual showroom with a free camera;
And so on. Unless they make a u-turn for the next GT, more tracks and cars won't change anything in the eyes of non-GT fans.