Concern #1: The Wizard gets outshined by the two new controllers, because their AoE's will tend to target "all enemies" while the wizard's mostly targets "all creatures".
I do not think this is the case. Controllers still hurt allies with most AoEs AFAIK.
This is hearsay, but what I have been hearing about the controllers is that druids are the most versatile and perhaps best at "controlling" on a round-to-round basis, invokers are a bit tougher and they tend to use summoning powers, and wizards still have the most potent dailies and are by far the most likely class to shut one or more enemies down completely.
Concern #2: The Sorcerer basically amounts to unofficially giving up on the Warlock as the arcane striker. The 'lock's damage output is sufficently behind the curve of other strikers that I fear the designers may have deemed it a lost cause.
I highly doubt it. The two classes look like they'll play very differently. The sorcerer seems like 100% glass cannon, while the warlock is much sneakier, much better at status effects, etc.
In fact, while they only have the first three levels of the class to play with, CharOp has failed to create an optimized sorcerer that outguns an optimized warlock, in terms of strict damage output, anyway. So basically, people are either panicking because the warlock is about to be obsoleted or panicking because they think the sorcerer is already obsoleted. I figure that's a good sign, if anything.
Concern #3: The [W] damage discrepency holds strong, or even broadens. Weapon users will continue to have a sizable boost in damage output over implement users. At first, I'd hoped the absence of martial characters in PHB2 would lead to righting the imbalance. However, on reflection, the only thing in the PHB2 that would really make a dent would be feats that reclaim some of the ground lost to superior weapons and various other weapon-boosting feats, or perhaps that help overcome Resists. Or something I just hadn't thought of.
I think this is a legitimate concern, and one that PHBII is unlikely to address. However, Arcane Power is likely to be a shot of pure crack to a number of implement-users.
Also: with the exception of the greatbow there isn't really any splatbook that has powered up ranged weapon attacks at the expense of ranged implement attacks. I think what we may be seeing is boosts to melee attacks to counteract the
inherent advantage of ranged and area attacks.