It's hard to know where WotC will be taking magic in the next incarnation of D&D, but from some of the discussions, one might infer something similar to 4th Edition's powers will make the cut as well as a Vancian-like system as a variant module (fire-and-forget spells similar to first, second and third edition D&D).
I'd like to suggest an alternative magic system from a flavor of D&D that not many people have experienced -- Dragonlance 5th Age. DL5A was based on the diceless SAGA Rules System (not related to the "Saga Edition" of the Star Wars RPG rules). DL5A used a playing card mechanic with stats in the 1 - 10 range. Magic was based on spell points which equalled the square of your appropriate stat (i.e. - somewhere between 36 to 81 points for a spell caster of above average Reason / Spirit). A sorcerer (mage) or mystic (cleric) could select from 1 to 3 schools/spheres of magical influence depending upon their stat. They could not cast spells outside their chosen school/sphere (a fire mage could not cast a spell with a water effect, for instance).
A spell's point cost was based on 5 components with a range of 1 to 5 in each. The spell's cost also determined its difficulty to cast successfully.
1) Invocation Time
3) Area of Effect (number of opponents or physical size as appropriate)
5) Spell Effect
To illustrate, a long invocation time (30 minutes) only cost 1 point where a quick (1 second) casting time would cost 5 points. Similarly, the spell affecting 1 person (1 point) is less expensive than a whole crowd of 20 or more people (5 points). The most expensive spells had a difficulty between 20 - 25 (which is a difficult challenge in the SAGA system). A "typical" spell might have a cost between 8 and 15 points.
The best part of the system is that it allowed spells to be created "on the fly" based upon your schools of magic. So, as a fire mage, I could spend fewer points for a small Burning Hands-like effect, or spend a lot more of my points for a larger Fireball. This can create a power curve that is similar to At-Will/Encounter/Daily in the sense that a mage must save up spell points for larger encounters and only use smaller spells whenever possible. Points were recovered at 1/hour so a mage or cleric would have to be careful about rationing points a high combat game (DL5A was a story-telling system, so combat was not inteneded to be the centerpiece of the system).
The challenge in adapting this system to a standard D&D model was the power curve. DL5A didn't have levels and hit points per se, but characters could take wounds equal to the value of cards in their hand (the average hand having about 25 - 30 points in it). Monsters/NPCs had a Phyique/Endurance score. Typical humanoid monsters had a physique less than 10 whereas a bear, ogre, or other large creature could have 10, 15 or even 20+ Physique.
Unlike in AD&D, these values do not scale up with levels. You could improve your hero in small ways as they get experience, but there was not the leveling power curve that you see in the traditional D&D rules. In 4e, the power curve is even steeper in terms of hit points, so translating the power of a spell from SAGA to D&D presents a real challenge.
The challenge, however, is worth examination as the SAGA magic system does have such a cool game flavor that it may be worth the trouble to try. In my next article, I will try to crunch some rough numbers to come up with a mechanic.
Read Part II here!