There's nothing to fix there. The consoles are under spec memorywise for a game like Rage. The texture loading is part of the concept of the engine. If the consoles had more memory or faster storage media, texture pop in or fade in would not be noticable. The other option would have been to lower texture resolution in general which would have had a greater negative impact on the visuals as it is now.
It's a miracle that Rage is running this good on ridiculously low 512MB at all!
Yeah the texture quality was lowered in Skyrim (for ps3 at least) and now they're ignoring people who have picked up on this. Frustrating.
Granted I'm no expert but how can the ps3 be under spec for rage if you look at the visuals in God of War 3? is it the scale of the game?