Everyone's seemed to concentrate exclusively on magical weapons, but what about armor, shields and general defensive type items that boost saving throws. It's going to be pretty rough for fighters and rogues to make Will saves against high level mind affecting spells with no bonus to their saving throw. A fighter with no magical weapons, armor or shield fighting high level monsters with high attack and damage bonuses such as giants and dragons is in for a really difficult time. The best AC that a fighter could hope for is AC 21 (full plate + large shield and a +1 dex bonus). For instance, a CR 10 monster like a fire giant has an attack bonus of +20/+15/+10 meaning that he's going to almost automatically hit on his first attack, probably hit on his second attack and have a 50/50 chance of hitting on his third attack. Magical Vestment helps but that's going to expend the cleric's already limited potential healing before the adventure even starts. What do fighters and rogues do against invisible creatures other than stand there and try to grope around looking for them?
Don't get me wrong, I'm not one of these people that advocates high level PC's as walking magic stores, but I just don't see fighters competing with wizards and even clerics for that matter without the assistance of magical weapons, armor and shields. Rogues are in a little better position because of their high sneak attack damage bonus and the evasion ability help them avoid the damage from the higher level damage spells, but I think that they also face a tough uphill battle without magical items. Clerics and wizards also aren't out of the woods, because once they run out of spells, the cleric becomes an inferior fighter and the wizard...well the wizard just gets a front row seat until he can replenish his spells the following day.
