No Vancian spellcasting above 3rd level spells. No Psionic powers above 3rd level. Spell-likes and (Su) abilities that emulate spells are still allowed because they are much harder to come by. Roleplay wise, the 'Wizard' archtype can either be filled with a standard low level Wizard or with a Warlock/DFA/Binder or any other class which is based on (Su) abilities. This also eliminates the silliness of level 9 Wizards being Gods. The 'God Wizard' archtype is still achievable but requires you to be a much higher level.
Thoughts? I feel like I must be missing something. I had this idea while studying and it just can't be that simple. The only thing I can't wrap my head around yet is how to deal with Scrolls and Racial spellcasting.