I don't know if it will, and I don't mind WotC experimenting with alternative systems to generate interest with folks who may be bored of the traditional D&D magic system, but I sure hope they don't give Vancian magic the boot.
I'd just like to see the system simplified a bit in 4E, with psionics thrown into the core as well but using its own 'psionic strength point'/'power point'-based manifestations and simplified further. Really wouldn't be hard. Other systems like Incarnum, Truenamers, and other stuff can be updated in their own supplements later.
Example:
4E PHB includes the Bard, using spontaneous arcane magic, with a spell list of mixed druid/wizard spells and a handful of unique bard spells that replace Bardic Music and have a duration of 'Concentration' with the caveat in their descriptions that the bard must continue singing, playing an instrument, chanting, or whatever to keep these spells active. Then it also includes the Sorcerer, with no spellcasting but a warlock-esque selection of spell-like abilities, not limited to fiendish stuff. Then it's got the Cleric, Druid, Ranger, and Paladin of course, with their prepared divine spells and maybe some limited spontaneous substitution capacity (cleric for domain spells and cure or inflict spells maybe, druid and ranger for SNA spells, paladin for cure spells). Then there's the Wizard, using the occasional Spell Mastery feat to make a spell (or a couple of spells) available for spontaneous substitution if he needs it, but otherwise casting prepared arcane spells. And the Psion and Psychic Warrior, or a singular Psionicist (I really did prefer 2E's kinda-roguish-basic-stats Psionicist with limited powers over 3E's division of the class), with their own reserve of psionic strength points, or psi, or mental stamina, or whatever, and a small selection of powers to learn.
For the casters, you got a small number of spell slots. Maybe a 1st-level wizard starts with 3 slots of 1st-level available each day, before factoring in any bonus slots. No 0-level slots; just bring back the old Cantrip 1st-level spell, that covers all the neat little utility purposes of cantrips. Detect Magic and Read Magic might be combined into one spell, See Magic, or just kept as separate 1st-level spells. Wizards and maybe others might have the option to substitute these two for any prepared spells when desired, since they're so basic and integral to the learning of magic. By 5th-level a wizard's spell slots may have changed to 1 of 3rd-level, 2 of 2nd-level, and 4 of 1st-level. By 9th-level it may have changed to 1 of 5th-level, 2 of 4th, 3 of 3rd, and 4 of 2nd. Lower-level spells can still be cast with higher-level slots, so the 2nd-level slots obviate the need for any 1st-level slots at that point. By 17th-level a wizard may have 1 slot of 9th-level, 2 of 8th, 3 of 7th, and 4 of 6th. By 20th, it could be 3 of 9th-level, 3 of 8th, 3 of 7th, and 3 of 6th. There might be spells like Rary's Mnemonic Enhancer or similar that allow the wizard to cast a few lower-level spells in place of a single upper-level slot, when he really doesn't want to waste more than 1 or 2 good slots on weak spells just because they're handy utility at the moment.
So even the most advanced non-epic caster only has 12 spell slots, plus any bonus slots. Specialization probably wouldn't grant bonus slots in this set-up, but a specialist wizard would probably get some other benefits that make his school's spells slightly more efficient and potent. Domains probably wouldn't grant extra spells either, a cleric would probably just count his domain spells as extra spells known, and ones that he or she could substitute spontaneously for other prepared spells. The Healing domain, or its successor, would probably give a more significant boost to healing spells if all clerics are able to sub-in Cures in 4E (since many of its spells would already be covered by that). But I dunno. Maybe Domains would be more like the old Spheres of spells, determining the cleric's spell list rather than just granting a few extra spells known.
Psionics would be even simpler, really. Get rid of the level-based set-up that 3E added; just make 3 or 4 tiers of powers. 1st-tier would be simplest in effect; Minor Telekinesis, Telekinetic Push, Telekinetic Strike, etc. Just a handful of effects for each discipline of psionics. Another, smaller handful for the 2nd-tier; more advanced ones that might replace the lower-tier prerequisite powers, or might be used alongside them (frex, Minor TK may be much cheaper in PSP/PP cost to manifest, but Greater TK might be much stronger and farther-reaching). And another, even smaller handful of powers per discipline for the 3rd-tier, which would combine aspects of lesser powers (True TK may be like a combination of Greater TK, Greater TK Push, Greater TK Strike, etc.). If a 4th-tier is used, it'd just be a narrower and more potent step-up from the 3rd-tier.
Access to the 2nd-tier would probably be around 5th-level, 3rd-tier around 10th-level, and 4th-tier around 15th-level, or if going with just 3, then 2nd-tier at 7th and 3rd-tier at 15th. The powers would have limited augmentation capacity or something, so a standard 1st-tier power may be like a 1st-level spell while a fully-augmented 1st-tier power may resemble a 3rd-level spell but slightly weaker and less efficient, for example.
Manifesters would probably have a proportionately much smaller reserve of power points than spellcasters have slots; a 1st-level psionicist may have enough PSP/PP to manifest 2 powers of the 1st-tier each day, before factoring in bonus points, while a 20th-level psionicist may be able to afford a maximum of 4 or 5 powers per day of the highest tier, before factoring in bonus points (which may be just enough for 1 more high-tier power); while he could eventually 'nova' a bit better than a mage (only in terms of being able to use their best powers for 1-3 rounds longer), the mage would still be blasting away fairly well for a full minute or two longer of intense combat (having fewer highest-level slots, but many next-highest-level and next-next-highest level slots). The psionicist's powers would also likely be a bit less potent anyway, when it comes to blasting.
And for Pete's sake, ditch the crystalpunk and psi-does-everything-magic-does nonsense of 3.5E psionics.