hmm...its not that simple.
Daily spell preparation is a way of balancing spells. In some context, hold, or charm person or fireball can be the winning spell, but you may not know that in the morning, so only prepare one or two. 3E added spontaneous casting, but with heavy limitations (to the point that sorcerers were often seen as 2nd class). 4E totally redid the power system, though it kept a strong fire and forget element, and spell preparation for wizards.
I don't think newE will have spell points or spell fatigue or skill/check based spells (though it could have some of that for psionics, and die rolling while casting could be more common, as in 4E). I don't think it will have Mage or Ars Magica make your spell type stuff (though it could eventually as a very optional option).
I think it will have:
*Discretely defined spells, with familiar names and effects.
*The caster will know some but not all of them. (Question, do clerics get to know all spells?).
*They will be organized into various buckets by power level.
*(with an exception for some at will magic, and that will be there) Only so many in a particular bucket will be castable in a given time period.
* Preparation will probably be there, but yes it may optional, though as with 3E or 4E wizards, strongly encouraged.
*There may also be other mechanics to limit "spamming" spells.
*The flavor of how spells are recovered may very and be totally non-vancian, even when the mechanics are quasi vancian, as they are across the board in all D&D, or vancian when the actual mechanics are sort of vancian lite, as in 4E.